bluuebunny/crossref_metadata_2025 huggingface dataset:
Estudo retrospectivo dos níveis de ácido hipúrico urinário em exames de toxicologia ocupacional
Authors: Gonzalez Kelly Cristina , Sagebin Fernando Rodrigues , Oliveira Paola Garcia , Glock Luiz , Thiesen Flavia Valladão
Published: July 2010

O ácido hipúrico é o principal metabólito do tolueno, solvente amplamente utilizado em processos industriais e com importantes efeitos tóxicos, fato que justifica a preocupação em monitorar regularmente sujeitos com risco de exposição ocupacional a este solvente. O objetivo deste trabalho foi avaliar os níveis de ácido hipúrico encontrados em trabalhadores submetidos à monitorização biológica. Foi realizado um estudo retrospectivo com dados dos anos de 2002 a 2005, no qual foram analisados os resultados e a situação do empregado na oportunidade do exame (periódico, demissional e admissional). Os resultados indicam uma redução significativa nos níveis de ácido hipúrico em 2005. Exames periódicos obtiveram resultados superiores aos exames admissionais e demissionais, e não foi verificada diferença significativa nas proporções dos sujeitos agrupados de acordo com a situação funcional em cada um dos intervalos estabelecidos segundo o valor de referência e o índice biológico máximo permitido. Os níveis de ácido hipúrico detectados indicam um baixo de risco de exposição ao tolueno na população avaliada, provavelmente em decorrência da preocupação crescente com a implantação de medidas de higiene ocupacional.
Percepção e utilização dos conteúdos de saúde coletiva por cirurgiões-dentistas egressos da Universidade Federal de Goiás
Authors: Badan Denise Elisabeth de Campos , Marcelo Vânia Cristina , Rocha Dais Gonçalves
Published: July 2010

A atualidade tem exigindo dos profissionais cirurgiões-dentistas o desafio de rever o conceito de atenção à saúde. As Diretrizes Curriculares Nacionais (DCN) sugerem mudanças na graduação, incentivando a consolidação do SUS. Objetivou-se conhecer a percepção e utilização dos conteúdos de saúde coletiva na prática dos egressos de 2000 a 2002, do curso de odontologia da Universidade Federal de Goiás. Utilizou-se a metodologia da triangulação de técnicas. Encontrou-se que 83,3% dos egressos trabalham como cirurgião-dentista. Continuaram os estudos cursando pós-graduações e especializações (68,1%). Têm dúvidas sobre as ações em saúde coletiva, embora as pratiquem. Atuar no serviço público determinou realizações de mais práticas em saúde coletiva. Os principais entraves ao desenvolvimento de ações em saúde coletiva foram falta de recursos materiais complementares e dificuldade de valorização pela população. O conteúdo recordado principal foi a promoção da saúde (100%) e o mais utilizado foi a prevenção, seguida de educação em saúde. As práticas de estágio extramuros foram muito valorizadas. Conclui-se que há necessidade de maior clareza, durante a graduação, sobre o que sejam práticas em saúde coletiva e maior integração curricular na graduação em odontologia.
Avaliação da fluoretação da água do sistema de abastecimento público na Ilha de São Luís, Maranhão, Brasil
Authors: Carmo Cadidja Dayane Sousa do , Alves Cláudia Maria Coelho , Cavalcante Paulo Roberto , Ribeiro Cecília Cláudia Costa
Published: July 2010

O objetivo deste estudo foi avaliar os níveis de flúor na água de abastecimento público da Ilha de São Luís (MA). Aplicou-se uma amostragem estratificada, considerando-se as estações de tratamento de água (06) e os bairros abastecidos (46). A análise dos teores de flúor na água foi feita através de um eletrodo específico. A concentração nas amostras variou de 0,05 a 0,84 ppm de flúor. Apenas uma estação de tratamento (Italuís) apresentou-se dentro do limite aceitável de fluoretação. A fluoretação da água de abastecimento público na Ilha de São Luís necessita de ajustes para se obter prevenção da cárie, evidenciando a importância de um controle externo para avaliação dos teores de flúor.
Depth-habitat reorganization of planktonic foraminifera across the Albian/Cenomanian boundary
Authors: Ando Atsushi , Huber Brian T. , MacLeod Kenneth G.
Published: July 2010

New mid-Cretaceous stable isotope (δ18O and δ13C) records of multiple planktonic foraminiferal species and coexisting coccoliths from Blake Nose (western North Atlantic) document a major depth-ecology reorganization of planktonic foraminifera. Across the Albian/Cenomanian boundary, deep-dwellingPraeglobotruncana stephaniandRotalipora globotruncanoidesadapted to living at a shallower depth, while, at the same time, the population of surface-dwellingParacostellagerina libycadeclined. Subsequently, the opportunistic speciesHedbergella delrioensisshifted to a deep environment, and the deep-dwelling formsRotalipora montsalvensisandRotalipora reichelifirst appeared. The primary paleoenvironmental cause of the observed changes in planktonic adaptive strategies is uncertain, yet their coincidence with an earliest Cenomanian cooling trend reported elsewhere implicates the importance of reduced upper-ocean stratification. Although there has been an implicit assumption that the species-specific depth habitats of fossil planktonic foraminifera were invariant through time, planktonic paleoecology is a potential variable. Accordingly, the possibility of evolutionary changes in planktonic foraminiferal depth ecology should be a primary consideration (along with other environmental parameters) in paleoceanographic interpretations of foraminiferal stable isotope data.
A Model for Water Injection Into Frac-Packed Wells
Authors: Suri Ajay , Sharma Mukul M.
Published: July 2010

Frac packs are increasingly being used for sand control in injection wells in poorly consolidated reservoirs. This completion allows for large injection rates and longer injector life. Many of the large offshore developments in the Gulf of Mexico and around the world rely on these completions for waterflooding and pressure maintenance. The performance of these injectors is crucial to the economics of the project because well intervention later in the life of the field is expensive and undesirable.

For the first time, we present a model for water injection in frac-packed wells. The frac pack and the formation are plugged because of the deposition of particles from the injected water, and their effective permeability to water is continuously reduced. However, as the bottomhole pressure (BHP) reaches the frac-pack widening pressure, the frac-pack width increases and a channel that accommodates additional injected particles is created.

Injectivity depends on the interstitial velocity of the injected water in the frac pack, volume concentration of the solids in the injected water, injection rate, injection-water temperature, size of proppants in the frac pack, width and length of the frac pack, and the initial minimum horizontal stress. In case of frac packs with large proppant size and high injection rates, the plugging of the frac pack is found to be negligible except in the building of a filter cake at the frac-pack walls. In the case of narrow frac packs with small proppant, significant plugging is expected, which leads to sharp permeability decline of the frac pack and a rapid rise in the BHP. The long-term injectivity of a frac-packed injector depends primarily on the filtration coefficient value of the frac pack, solids concentration in the injected water, and the injection rate. Frac packs are expected to maintain higher injectivities compared to any other completions such as openhole, cased-hole, perforated, or gravel packs.
Theoretical and Experimental Investigation of Water-in-Oil Transverse Dispersion in Porous Media
Authors: Duan Shengkai , Wojtanowicz Andrew K.
Published: July 2010

Water production is controlled by the size and distribution of water saturation around wells. A recent discovery shows that not employing hydrodynamic mixing in numerical simulators may underestimate the water transition zone (Duan and Wojtanowicz 2006). This paper reports continuing research into mechanisms causing expansion of the water-saturation transition zone (transverse dispersion) in a segregated flow of oil and water approaching a vertical well's completion. The mechanisms—including nonlinear flow, turbulence, shear rate, and flow baffling at grains—all contribute to the instability of the oil/water interface, resulting in hydrodynamic mixing. Interface instability because of shearing rate has been demonstrated in our recent study on the Hele-Shaw model (Duan and Wojtanowicz 2007). In this paper, we mathematically model the effect of flow baffling and demonstrate transverse dispersion experimentally using a linear physical sandpack.

A simple model of tortuous flow was developed to demonstrate the effect of two-phase-flow baffling in granular porous media. The model shows that the change in flow momentum of the two fluids at the point of collision with rock grains becomes the major factor causing water dispersion.

A series of segregated-flow runs (top, oil; bottom, water) was carried out using a physical model packed with different porous media at a constant pressure drop. The runs were videotaped and analyzed for saturation distribution using a color-intensity-recognition software. The results clearly demonstrate onset of transverse dispersion of water into the flowing oil. Further dispersion, however, was overshadowed by the dimensional and end-point effects of the model. With a numerical estimation procedure, the initial dispersion rate—computed from the 1D flow model—is the essential data needed to estimate total dispersion in radial inflow to wells.
Parallelization of a Commercial Streamline Simulator and Performance on Practical Models
Authors: Batycky R.P.. P. , Förster M.. , Thiele M.R.. R. , Stüben K..
Published: July 2010

We present the parallelization of a commercial streamline simulator to multicore architectures based on the OpenMP programming model and its performance on various field examples. This work is a continuation of recent work by Gerritsen et al. (2009) in which a research streamline simulator was extended to parallel execution.

We identified that the streamline-transport step represents approximately 40-80% of the total run time. It is exactly this step that is straightforward to parallelize owing to the independent solution of each streamline that is at the heart of streamline simulation. Because we are working with an existing large serial code, we used specialty software to quickly and easily identify variables that required particular handling for implementing the parallel extension. Minimal rewrite to existing code was required to extend the streamline-transport step to OpenMP. As part of this work, we also parallelized additional run-time code, including the gravity-line solver and some simple routines required for constructing the pressure matrix. Overall, the run-time fraction of code parallelized ranged from 0.50 to 0.83, depending on the transport physics being considered.

We tested our parallel simulator on a variety of large models including SPE 10, Forties-a UK oil/water model, Judy Creek-a Canadian waterflood/water-alternating-gas (WAG) model, and a South American black-oil model. We noted overall speedup factors from 1.8 to 3.3x for eight threads. In terms of real time, this implies that large-scale streamline simulation models as tested here can be simulated in less than 4 hours. We found speedup results to be reasonable when compared with Amdahl's ideal scaling law. Beyond eight threads, we observed minimal speedups because of memory bandwidth limits on our test machine.
Analysis of the Effect of Residual Oil on Particle Trapping During Produced-Water Reinjection Using X-Ray Tomography
Authors: Saraf A.. , Zwart A.H. de , Currie Peter K. , Ali Mohammad A.J.
Published: July 2010

Recently, it has been shown that the presence of residual oil in a formation can have a considerable influence on the trapping mechanisms for particles present in reinjected produced water (Ali 2007; Ali et al. 2005, 2007, 2009). This article reports on a further set of extensive coreflow experiments that confirm and extend these results. The tests were conducted in a computerized-tomography (CT) scanner, allowing direct observation of the buildup of particle deposition along the core.

These experiments are relevant to operational issues associated with produced-water reinjection (PWRI). In many cases, produced water is injected into formations containing oil, so reduced oil saturation is achieved rapidly in the area around the well. Even if the well is outside the oil zone, trapped oil droplets are always present in produced water, and a residual-oil zone will gradually build up around the well.

Major differences are found between the deposition profiles for fully water-saturated cores and the cores having residual-oil saturation. In particular, particles penetrate deeper into the core with residual-oil saturation, and considerably more particles pass completely through the core without being trapped. The X-ray technique allows direct observation during the experiment of the deposition process inside the core, eliminating the complicating effect of any external filter cake. As a result, an analysis can be performed of the deposition parameters relevant inside the core using deep-bed-filtration theory, and the results of this analysis are presented. In particular, it is shown that the values of the filtration function determined from the CT-scan (X-ray) data are consistent with those obtained from analysis of the effluent concentration. Moreover, both methods of analysis find quite clearly that the filtration coefficient increases with decreasing flow rate.

The results indicate that formation damage near a wellbore during water injection will be reduced by the presence of residual oil, and that particles will penetrate deeper into the formation. The result is also relevant to injection under fracturing conditions because particle deposition in the wall of the fracture (where residual oil may be present) is one of the mechanisms governing fracture growth.
Bringing the First BP-Operated Subsea-to-Shore Gas Field Into Production: Flow-Assurance Lessons Learned
Authors: Harun A.F.. F. , Watt N..
Published: July 2010

Taurt field, located in the Mediterranean Sea in 108-m water depth, is the first BP-operated subsea-to-shore gas development. Phase 1 of the project consists of two subsea wells producing directly from the subsea manifold to the onshore gas-processing plant with a 68-km, 20-in. pipeline. The field has been brought into production and was successfully ramped up to 230 MMscf/D despite facility constraints during initial startup. The main flow-assurance issues experienced during the initial startup are hydrate risks because of Joule-Thomson (J-T) cooling and liquid-production handling onshore, particularly because of potential completion-brine return.

The experience during initial startup highlights the importance of collecting good fluid samples during exploration and appraisal, and obtaining downhole and wellhead pressures and temperatures during flowback. Confirming the condensate yield helps prediction of liquid holdup in the pipeline that will affect the prediction of liquid production coming onshore during ramp up. More-accurate prediction of the wellhead temperature affects the requirement for hydrate inhibitor, which also affects the liquid holdup in the pipeline and liquid production coming onshore.

Transient simulations help in selecting the dewatering strategy to be either a pigged or a pigless operation by predicting the amount of remaining water and how it impacts the production ramp up. Simulations also help prediction of the liquid production for setting up temporary liquid-handling facilities to prevent the possibility of completion-brine return upsetting the processing plant.

Comparison with the actual liquid-production data suggests that simulations should have been performed with less-conservative condensate yield, although predicting the completion-brine return onshore is still difficult. After obtaining the latest fluid composition and the actual operating conditions, the hydrate-management strategy was revisited, and this resulted in cost savings and simpler operating procedures.
Analysis of Threaded Connection Reliability for Compression Application
Authors: Alves Paul , Forcinito Mario , Xu Jason , Ferguson Matthew , Tardif Philip , Jensen Paul
Published: July 2010

The objective of this paper is the investigation and evaluation of the performance and life expectancy of NPT threaded connections as applied to a particular type of reciprocating compressor unit.

The study focused on the assessment of the levels of excitation forces acting on the threaded connections and the resulting stress. These forces and stresses were determined from field vibration measurement results applied to a mechanical model of the system.

As an extensive literature search did not yield satisfactory data for specific fatigue properties of NPT connections, we applied a first-principles approach to the problem and calculated the stress concentration factors from a detailed finite element study of the thread engagement under axial and circumferential loads. The results and details are reported here.

Stress levels determined by this methodology were compared to the allowable fatigue limits for the piping and valves materials and a life expectancy was calculated.

The same methodology can be applied to other situations involving threaded connections.
Devonian Gas Exploration in Northeastern British Columbia: Geology, Operations and Economics
Authors: Gray F.F. , Kassube J.R. , Van de Venter J.H.
Published: July 2010

Following indications of Devonian gas in several widely scatterednortheastern British Columbia wildcats drilled between 1954 and 1956, anaggressive programme of exploration for Middle Devonian gas was begun in the Fort Nelson area in the winter of 1956–57. Since this time the explorationeffort for Devonian gas has steadily increased, with new operators entering theplay, and new discoveries being added each year.

All of these discoveries to date are in Middle Devonian beds, with theexception of the Pacific-Imperial Parkland well, which produces from the Upper Devonian Wabamun formation on the Peace River Arch. The discoveries lieentirely in the Plains area with the exception of Beaver River, which is in thefolded belt at the extreme northern edge of the Province.

Most of the Middle Devonian fields discovered to date are in reefalcarbonates associated with the rim of a shale embayment which extends southeastinto British Columbia from the Yukon territory. Exploration for these fields isguided by a combination of seismic and subsurface stratigraphic methods. Faciesanalysis is particularly important to delineate favourable carbonateenvironments.

Seismic operations and costs run about $70,000.00 per month and are affectedsignificantly by local terrain and weather conditions. Construction andmaintenance of access roads and trucking of rigs and supplies into the bush arealso major exploration expenses. In the drilling of exploratory wells for Middle Devonian gas, it has been common practice to set 300 feet of 13 3/8"surface casing, 2000 to 2500 feet of 9 5/8"intermediate casing through upper Mississippian porous carbonates, 7" casing to the top of the Slave Pointformation, and a 5" liner through the productive zone. Development wells can becompleted in open hole beneath the 7" casing, usually giving higher absoluteopen flow and deliverability rates.

With increasing activity drilling costs have been steadily reduced. In theimmediate area of Fort Nelson wells can now be drilled to the Slave Point in 20to 25 days for as little as $100,000.00 and an open hole completion made for$150,000.00. At more remote locations, costs have been appreciably higher.
Development and Application of a Fully-coupled Two-dimensional Finite Element Approach to Deformation and Pressure Diffusion Around a Borehole
Authors: Cheng H. , Dusseault M.B.
Published: July 2010

The fully-coupled deformation and diffusion behaviour around a boreholedrilled in a fluid-saturated poroelastic medium are modelled using atwo-dimensional finite element method. A variational principle equivalent tothe governing equations in the theory of poroelasticity is derived. Thevariational principle used here to achieve a full coupling is notconventionally employed in porous medium mechanics, therefore verificationprocedures were implemented.

The distribution and the history of effective stresses and pore pressurearound the borehole, valuable factors for evaluation of borehole stability andsolids production potential, are evaluated in hydrostatic and non-hydrostaticstress fields, and under different wellbore pressures. For typical cases thatcorrespond to oil field conditions, significant differences are found betweenthe fully-coupled solution and the uncoupled solution.

Introduction

The basic equations for coupling elastic deformation with pore pressure forporous media subjected to transient fluid flow were first established by Biotin 1941. There have since been numerous restatements given, and Rice and Cleary provide an particularly elegant reformulation of Biot theory byredefining the material constants. The theory of poroelasticity not onlypredicts quantitative differences from uncoupled flow-deformation theory, italso predicts phenomena such as the Mandel-Cryer effect, which are neitherintuitive nor revealed by the uncoupled theories. It has become the preferredapproach in many geomechanical applications, but because of the governingequations' complexity, analytical or closed-form solutions are available onlyfor cases of simple geometry and boundary conditions. For example, a recentdevelopment by Wang and Dusseault provides a solution for fullyporoelastic coupling in an axisymmetric plane strain borehole subjected toinjection or withdrawal.

The complexities of the governing equations coupling deformation withdiffusion, combined with the strongly non-linear behaviour of geomaterials, naturally increase the importance and popularity of numerical approaches. The Finite Element Method (FEM) is the most widely used procedure for numericallyapproximating the theory of poroelasticity. In cases involving coupleddeformation-diffusion, there are two formulations of FEM commonly employed tosolve boundary value problems.
The Effect of Shear Failure on the Cyclic Steam Process and New Pseudo Functions for Reservoir Simulation
Authors: Ito Y. , Settari A. , Jha K.
Published: July 2010

The steam stimulation process is a proven, commercially viable recoveryprocess in oil sand reservoirs. However, an understanding of the recoverymechanism is far from complete. Recent studies of the geotechnical aspects oftar sands point to the importance of shear failure created by pore pressureincrease on fluid flow in the reservoir during steam injection. The changes inmass and heat transport properties in the heterogeneously deformed failure zonehave been shown to be important factors for the recovery mechanism. This paperdescribes the theoretical and practical aspects of representing the shearfailure zone in reservoir simulation, by the means of pseudo relativepermeability functions.

Relative permeability hysteresis is commonly used in the simulation of thesteam stimulation process, but its mechanism is not clear. The paper reviewsthe existing methods for treating hysteresis and gives the theory for thepseudo relative permeabilities caused by heterogeneously failed media. The newfunctions are derived by considering the shear failure phenomenon. A new set ofstress-dependent pseudo relative permeabilities is proposed and a practicalmethod for the use of the pseudo functions (including hysteresis) in areservoir simulator is given. The method applies to injection as well asproduction cycles. Its effect on simulating the cyclic steam process is givenin examples and shows that the hysteresis should be stress-dependent ratherthan saturation-dependent.

Introduction

When the same set of water-oil relative permeability data is used tosimulate the injection and production periods of a cyclic steam stimulationprocess in tar sands or a heavy oil reservoir, the simulated water-oil ratiosare usually much greater than those observed in the field. To achieve a bettermatch of field data in the reservoir simulator, a higher relative permeabilityto water is used during the injection period than that used during theproduction period. The use of this technique in simulating a cyclic steamstimulation process is reported in a number of papers. It is based on theresults of laboratory studies on the hysteresis phenomenon of relativepermeability which will be briefly reviewed.
Production Problems in the Steam-stimulated Shaley Oil Sands of the Cold Lake Reservoir: Cause and Possible Solutions
Authors: Chakrabarty T. , Longo J.M.
Published: July 2010

The highly viscous bitumen from the Cold Lake reservoir in Alberta isproduced by the Cyclic Steam Stimulation (CSS) process. The clean oil sands ofthe Cold Lake reservoir generally produce well, but the shaley oil sands withimbedded clasts have experienced lower bitumen production and lower steaminjectivity.

This paper presents laboratory and field data that support the hypothesisthat the minerals in the clasts play a role in the production problems of theshaley oil sands. Laboratory tests reveal that clasts in the shaley oil sandshave an abundance of carbonate minerals such as siderite (iron carbonate) andaluminosilicate minerals such as kaolinite and feldspar. Laboratory studiesunder steam stimulation conditions show that the mineral reactions betweencarbonates and aluminosilicates can generate formation damaging products suchas swelling clay and carbon dioxide. Swelling clay can damage the formation byplugging the pore throats, whereas carbon dioxide can lead to near-wellborescaling. Calcium carbonate scales have been observed in downhole pumps andliners in Cold Lake wells. The field bitumen production appears to be inverselycorrelated with the carbonate content of the clasts. The field bitumenproduction is also inversely correlated with the amount of carbon dioxidegenerated in the laboratory by hydrothermal reactions of clasts. The paperdescribes the application of portable X-ray fluorescence (XRF) andnear-infrared instruments for rapid, nondestructive identification of reactiveminerals in cores, and of photoelectric absorption (Pe) logs for identifyingshaley oil sands with reactive minerals. It proposes diagnostic tests toidentify the extent and type of damage in a producing well. Finally, itdiscusses several potential methods for formation damage remediation andprevention.

Introduction

Cold Lake reservoir in northeastern Alberta has a vast resource base of oilsands. The bitumen in the oil sands has a viscosity of about 100,000 cp atreservoir temperature. Imperial Oil Resources Limited is using the Cyclic Steam Stimulation (CSS) process to recover the bitumen. The wells are drilleddirectionally from one surface location and there are twenty wells in one pad. In one cycle, steam is injected over a period of 30 to 40 days, and a hotbitumen and water mixture is produced over several months. Each well goesthrough several cycles of injection and production until steam injectionbecomes uneconomic.
Concentric Coiled Tubing Application for Sand Cleanouts in Horizontal Wells
Authors: Falk K. , Fraser B.
Published: July 2010

The evolution of coiled tubing technology has brought many unique wellservice solutions to the oil and gas industry. Concentric Coiled Tubing (CCT)is a recent development which has opened the door to a whole range of new wellservicing capabilities. One of these techniques incorporates concentric coiledtubing equipment with a patented jet pump tool (SandVacSM, US patentnumber 5,033,545) specifically for the purpose of cleaning sand out of lowpressure horizontal wells. This paper will discuss cleanout issues and how the SandVacSM process provides an improved solution to cleaning in lowpressure, horizontal wells. To summarize, a review and discussion of the firstfive Sand-VacSM field applications will be given.

Introduction

Sand production is often a serious problem for heavy oil producers. Whensuspended in the produced flow, sand can cause destructive abrasion of pumpingequipment. On surface, the operator must deal with separation, handling andfinally, disposal of potentially large quantities of contaminated fines. Themost serious consequence of sand production however, is when deposition occursin the completion. Settled quantities of sand in the completion will impedefluid flow and therefore impede production. This problem is compounded by thefact that heavy oil producers are turning to horizontal well technology tomaximize production. Compared with vertical wells, horizontal wells have thefollowing characteristics:A longer interface for sand-inflowPerpendicular orientation of fluid flow and settling velocity vectorsSlight horizontal trajectory undulations-resulting in "troughing"

Each of these conditions has a significant effect on the amount of sandaccumulation in the completion.

Sand Control

A number of methods have been used to try to prevent sand inflow. Totalexclusion techniques employ a formation barrier designed to prevent any solidsfrom entering the completion. This technique is often very expensive and canresult in severe skin effects at the barrier(l). A more cost effectiveinstallation uses a "partial exclusion" approach. Usually, this takes the formof a liner in which specifically sized slots have been cut. The liner thenpreserves the hole integrity while the slots allow oil inflow.
An Experimental Investigation of Convergent Flow To Horizontal Wells
Authors: Suprunowicz R. , Butler R.M. , Ford C.O.K. , Kry S.F.
Published: July 2010

If the problem of fluid flow in a reservoir toward a well cannot beapproximated as a two-dimensional one, the analytical treatment becomes verydifficult. This is especially true when horizontal wells are involved and theend-effect cannot be neglected.

There are, in the literature, mathematical expressions to calculateproductivity of horizontal wells for various geometric configurations and manyof these include the effect of flow convergence. Some of them appear to besignificantly in error.

The paper describes experiments with an electrolytic model. This approachuses the analogy between the flow of fluid particles, driven by fluidpotential, in a porous medium and movement of ions, driven by electricalpotential, in an electrolyte. A simple and low-cost experimental setup permitsthe testing of various theoretical equations and the results are presented.

Introduction

In many cases the flow of fluids in a homogeneous reservoir toward a well, vertical or horizontal, can be analyzed simply when the problem istwo-dimensional. In some situations this approach may be sufficient; but when, because of more complicated geometry, the effect of convergence toward the tipof a well (as, for example, in the case of a vertical well partiallypenetrating a liquid- bearing porous matrix layer) has to be taken intoaccount, the difficulties of establishing the flow pattern and, consequently, calculations of the well productivity, may be significant.

A common simplification is the assumption of the uniform flux along theactive well length. But this approach, as pointed out by Muskat(l), does notgive the correct results, even for the relatively simple case of a partiallypenetrating vertical well and steady-state flow.

The situation becomes more difficult for horizontal wells of finite lengthdraining bounded volumes. There is usually a problem of convergent flow towarda well in a plane perpendicular to the well's axis, but on top of this there isa three-dimensional convergence toward the tips of the well. Probably in somesituations when, for example, the well is very long and draining a thin layerand narrow pattern, this additional convergence can be neglected.
Analysis of KLa Measurement Methods in Stirred Vessels: The Role of Experimental Techniques and Fluid Dynamic Models
Authors: Pinelli Davide , Liu Zuohua , Magelli Franco
Published: July 2010

Several dynamic and steady-state methods have been proposed in the literature for measuring the mass transfer coefficient in gas-liquid stirred vessels. Analysis has also been developed about the fundamentals of the most interesting techniques. Similarly, the flow behaviour of the gas and the liquid phases has been modelled in various waysthe different models often resulting in different coefficient estimates. Cross checking of a number of techniques and of various models has already been performed for a number of cases. However, not all the implications are clear and have been retained, especially for high-aspect-ratio equipment stirred with multiple impellers.In this paper, the main problems in KLa characterisation are analysed: the most promising techniques and flow models are reviewed critically and several combinations of experimental methods and models have been tested with the purpose of providing information regarding their choice. Vessels stirred with sets of multiple impellers of different types as well as coalescing and non-coalescing gas-liquid systems have been considered. Recommendations about the use of some of the mentioned tools are also given in relation to the final use of the coefficient.
Microwave-Enhanced Alkali Catalyzed Transesterification of Kenaf Seed Oil
Authors: Rathana Yuong , Roces Susan A. , Bacani Florinda T. , Tan Raymond R. , Kubouchi Masatoshi , Yimsiri Piyachat
Published: July 2010

A two-step process assisted by microwave irradiation was used to produce kenaf oil methyl ester. The first stage made use of sulfuric acid catalyst to convert free fatty acids into methyl ester, while the second made use of potassium hydroxide catalyst under microwave irradiation to transesterify the triglycerides. The four major experimental variables considered in the latter step were catalyst concentration, alcohol-oil molar ratio, reaction temperature and reaction time. The results were analyzed statistically for the effect of those variable parameters on the reaction conversion. Optimum conversion of about 94% was obtained at the optimum values of variables 0.55% KOH catalyst, 4.5:1 methanol-oil molar ratio, 57.5oC and 6.5 minutes reaction time. The analyses on the biodiesel produced by this method proved to be acceptable in comparison to ASTM biodiesel standard.
Analytical Solution of Linear and Non-Linear Space-Time Fractional Reaction-Diffusion Equations
Authors: Yildirim Ahmet , Sezer Sefa A
Published: July 2010

In this study, we present the homotopy perturbation method (HPM) for finding the analytical solution of linear and non-linear space-time fractional reaction-diffusion equations (STFRDE) on a finite domain. These equations are obtained from standard reaction-diffusion equations by replacing a second-order space deri-vative by a fractional derivative of order and a first-order time derivative by a fractional derivative of order. Some examples are given. Numerical results show that the homotopy perturbation method is easy to implement and accurate when applied to linear and non-linear space-time fractional reaction-diffusion equations.
Regular Infinite Economies
Authors: Covarrubias Enrique
Published: July 2010

The main contribution of this paper is to place smooth infinite economies in the setting of the equilibrium manifold and the natural projection map à la Balasko. We show that smooth infinite economies have an equilibrium set that has the structure of a Banach manifold and that the natural projection map is smooth. We define regular and critical economies, and regular and critical prices, and we show that the set of regular economies coincides with the set of economies whose excess demand function has only regular prices. Generic determinacy of equilibria follows as a by-product.
Chronic Administration of the Glucagon-Like Peptide-1 Analog, Liraglutide, Delays the Onset of Diabetes and Lowers Triglycerides in UCD-T2DM Rats
Authors: Cummings Bethany P. , Stanhope Kimber L. , Graham James L. , Baskin Denis G. , Griffen Steven C. , Nilsson Cecilia , Sams Anette , Knudsen Lotte B. , Raun Kirsten , Havel Peter J.
Published: July 2010

OBJECTIVE

The efficacy of liraglutide, a human glucagon-like peptide-1 (GLP-1) analog, to prevent or delay diabetes in UCD-T2DM rats, a model of polygenic obese type 2 diabetes, was investigated.

RESEARCH DESIGN AND METHODS

At 2 months of age, male rats were divided into three groups: control, food-restricted, and liraglutide. Animals received liraglutide (0.2 mg/kg s.c.) or vehicle injections twice daily. Restricted rats were food restricted to equalize body weights to liraglutide-treated rats. Half of the animals were followed until diabetes onset, whereas the other half of the animals were killed at 6.5 months of age for tissue collection.

RESULTS

Before diabetes onset energy intake, body weight, adiposity, and liver triglyceride content were higher in control animals compared with restricted and liraglutide-treated rats. Energy-restricted animals had lower food intake than liraglutide-treated animals to maintain the same body weights, suggesting that liraglutide increases energy expenditure. Liraglutide treatment delayed diabetes onset by 4.1 ± 0.8 months compared with control (P < 0.0001) and by 1.3 ± 0.8 months compared with restricted animals (P < 0.05). Up to 6 months of age, energy restriction and liraglutide treatment lowered fasting plasma glucose and A1C concentrations compared with control animals. In contrast, liraglutide-treated animals exhibited lower fasting plasma insulin, glucagon, and triglycerides compared with both control and restricted animals. Furthermore, energy-restricted and liraglutide-treated animals exhibited more normal islet morphology.

CONCLUSIONS

Liraglutide treatment delays the development of diabetes in UCD-T2DM rats by reducing energy intake and body weight, and by improving insulin sensitivity, improving lipid profiles, and maintaining islet morphology.
Large Copy-Number Variations Are Enriched in Cases With Moderate to Extreme Obesity
Authors: Wang Kai , Li Wei-Dong , Glessner Joseph T. , Grant Struan F.A. , Hakonarson Hakon , Price R. Arlen
Published: July 2010

OBJECTIVE

Obesity is an increasingly common disorder that predisposes to several medical conditions, including type 2 diabetes. We investigated whether large and rare copy-number variations (CNVs) differentiate moderate to extreme obesity from never-overweight control subjects.

RESEARCH DESIGN AND METHODS

Using single nucleotide polymorphism (SNP) arrays, we performed a genome-wide CNV survey on 430 obese case subjects (BMI >35 kg/m2) and 379 never-overweight control subjects (BMI <25 kg/m2). All subjects were of European ancestry and were genotyped on the Illumina HumanHap550 arrays with ∼550,000 SNP markers. The CNV calls were generated by PennCNV software.

RESULTS

CNVs >1 Mb were found to be overrepresented in case versus control subjects (odds ratio [OR] = 1.5 [95% CI 0.5–5]), and CNVs >2 Mb were present in 1.3% of the case subjects but were absent in control subjects (OR = infinity [95% CI 1.2–infinity]). When focusing on rare deletions that disrupt genes, even more pronounced effect sizes are observed (OR = 2.7 [95% CI 0.5–27.1] for CNVs >1 Mb). Interestingly, obese case subjects who carry these large CNVs have moderately high BMI and do not appear to be extreme cases. Several CNVs disrupt known candidate genes for obesity, such as a 3.3-Mb deletion disrupting NAP1L5 and a 2.1-Mb deletion disrupting UCP1 and IL15.

CONCLUSIONS

Our results suggest that large CNVs, especially rare deletions, confer risk of obesity in patients with moderate obesity and that genes impacted by large CNVs represent intriguing candidates for obesity that warrant further study.
Fetal Exposure to Maternal Type 1 Diabetes Is Associated With Renal Dysfunction at Adult Age
Authors: Khalil Charbel Abi , Travert Florence , Fetita Sabrina , Rouzet François , Porcher Raphael , Riveline Jean-Pierre , Hadjadj Samy , Larger Etienne , Roussel Ronan , Vexiau Patrick , Le Guludec Dominique , Gautier Jean-François , Marre Michel
Published: July 2010

OBJECTIVE

In animal studies, hyperglycemia during fetal development reduces nephron numbers. We tested whether this observation translates into renal dysfunction in humans by studying renal functional reserve in adult offspring exposed in utero to maternal type 1 diabetes.

RESEARCH DESIGN AND METHODS

We compared 19 nondiabetic offspring of type 1 diabetic mothers with 18 offspring of type 1 diabetic fathers (control subjects). Glomerular filtration rate (51Cr-EDTA clearance), effective renal plasma flow (123I-hippurate clearance), mean arterial pressure, and renal vascular resistances were measured at baseline and during amino acid infusion, which mobilizes renal functional reserve.

RESULTS

Offspring of type 1 diabetic mothers were similar to control subjects for age (median 27, range 18–41, years), sex, BMI (23.1 ± 3.7 kg/m2), and birth weight (3,288 ± 550 vs. 3,440 ± 489 g). During amino acid infusion, glomerular filtration rate and effective renal plasma flow increased less in offspring of type 1 diabetic mothers than in control subjects: from 103 ± 14 to 111 ± 17 ml/min (8 ± 13%) vs. from 108 ± 17 to 128 ± 23 ml/min (19 ± 7%, P = 0.009) and from 509 ± 58 to 536 ± 80 ml/min (5 ± 9%) vs. from 536 ± 114 to 620 ± 140 ml/min (16 ± 11%, P = 0.0035). Mean arterial pressure and renal vascular resistances declined less than in control subjects: 2 ± 5 vs. −2 ± 3% (P = 0.019) and 3 ± 9 vs. −14 ± 8% (P = 0.001).

CONCLUSIONS

Reduced functional reserve may reflect a reduced number of nephrons undergoing individual hyperfiltration. If so, offspring of type 1 diabetic mothers may be predisposed to glomerular and vascular diseases.
Reducing Death in Malaria by Using Artemisinin Preparations
Authors: Faiz MA , Gomes MF
Published: July 2010

DOI: 10.3329/jom.v11i2.5449J MEDICINE 2010; 11 : 106-107
Association Between Acute Stroke and Metabolic Syndrome
Authors: Iqbal Md Jabed , Siddiqui Md Mahmudur Rahman , Islam Quazi Tarikul , Hossain Ahmed , Mustafa Ekramul , Shipa Md Ruhul Amin , Rahman Md Yousuf Ur , Sina Hashmi
Published: July 2010

Objective: Metabolic syndrome is the cluster of vascular risk factors including insulin resistance, elevated bloodpressure, hyperlipidemia, and obesity. Metabolic syndrome is strongly associated with cardiovascular andcerebrovascular disease. The aim of this study is to find out association between stroke and metabolic syndrome inour population.Methods: In this observational study, a total number of fifty randomly selected patients were studied from July2009 to December 2009 at Medicine ward of Dhaka Medical College Hospital. Definition of metabolic syndromewas taken from the guidelines by the National Cholesterol Education Program Adult Treatment Panel III.Results: Among the study population 46% had metabolic syndrome. This study estimated that Ischaemic stroke ismore common among metabolic syndrome patients (65.2%), but patient without metabolic syndrome had morehaemorrhagic stroke (55.6%).Only 12% patient was found obese. With or without metabolic syndrome most of thepatient had elevated TG (64%) and raised blood pressure (64%).Conclusion: Without obesity, metabolic syndrome is an important risk factor for cerebrovascular disease. Majorityof the patients with metabolic syndrome present as ischemic stroke.Keywords: Stroke; Metabolic syndrome; hypertension; fasting blood sugar; hyperlipidaemia.DOI: 10.3329/jom.v11i2.5453J MEDICINE 2010; 11 : 124-127
Management Difficulties of Cerebeller Haemangioblastoma: A Case Report and Literature Review
Authors: Chowdhury Forhad Hossain , Haque Md Raziul , Islam Md Shafiqul , Sarkar Mainul Haque , Alam Syed Mahbubul
Published: July 2010

The surgical removal of solid deep-seated haemangioblastomas remains challenging, because treatment of theselesions is often complicated by severe bleeding associated with the rich vascularity of this tumor and by severe neuraltissue injury associated with the difficulty of en bloc resection. A 55 year-old man, was admitted to us with inability tostand & walk due to imbalance and altered level of conciousness .He has family history of Von Hippel Lindau(VHL)disease. He underwent microsurgery followed by gamma knife radiosurgery 13 years back for cerebellerhaemangioblastoma. Magnetic resonance imaging (MRI) revealed intra-axial mass with multiple large cysts incerebellum with severe compression on cerebellum and brainstem. Preoperative angiography revealed a hypervasculartumor in the posterior fossa, he underwent microsurgery through the previous midline suboccipital craniotomyinvolving the removal of the arch of C-1. Patient recovered slowly in post operative period.Keywords: Cerebeller haemangioblastoma; Von Hippel Lindau disease; Radiosurgery; MicrosurgeryDOI: 10.3329/jom.v11i2.5463J MEDICINE 2010; 11 : 155-158
Dural Arteriovenous Fistula - A Review
Authors: Khan Sharif Uddin , Siddiqui Md Mahmudur Rahman , Rahman Kazi Mohibur , Hoque Md Azharul , Mondol Md Badrul Alam , Habib Mansur , Mohammad Quazi Deen
Published: July 2010

DOI: 10.3329/jom.v11i2.5464J MEDICINE 2010; 11 : 159-166
Melanosis Coli - An Atypical Presentation
Authors: Ahasan HAM Nazmul , Khan Mohammad Ashik Imran , Mahbub Md Shahriar , Alam Md Billal , Miah Md Titu , Gupta Ratan Das , Arif Khan Mohammad
Published: July 2010

Melanosis Coli is described as black or brown discoloration of the mucosa of the colon. It is a benign condition, whicharises from anthraquinone laxative abuse and usually has no symptoms of its own. Though not a very rare condition,to the best of our knowledge, no case has been reported on melanosis coli in Bangladesh . Here we report a case ofmiddle aged lady presenting with passage of blood mixed stool for one year. Colonoscopy was performed whichrevealed melanosis coli and which was later confirmed by histopathology. Not thought to be a pre malignantcondition, it has been found in some patients with other diseases.Keywords: Melanosis coli; Anthraquinone; Lipofuscin; Laxative; BangladeshDOI: 10.3329/jom.v11i2.5469J MEDICINE 2010; 11 : 183-185
Multiple Bone Hemangiomas Presenting As Bony Metastasis of Unknown Primary
Authors: Daoud Ehab
Published: July 2010

Bone hemangiomas are rare benign tumors of the bones of vascular origin. A patient with bony pains and abnormalradiological findings is described. Following an unsuccessful extensive search for primary malignancy the patient wasdiagnosed as multiple bone hemangioma. This case serves as a reminder for considering benign causes of bonelesion while investigating cases with such presentation.Keywords: Hemangioma; multiple; sclerosing hemangioma; back painDOI: 10.3329/jom.v11i2.5473J MEDICINE 2010; 11 : 196-199
An Old Man with Unusual Precordial Pain
Authors: Albuquerque Polianna LMM , Costa Larizza B , Bastos Breno B , Albuquerque Alex Karrel S , Vasconcelos Deborah N , Silva Geraldo B
Published: July 2010

We describe an interesting case of unusual origin of precordial pain. A 75-year-old man was admitted to theEmergency Room of José Frota Institute, Fortaleza city, Brazil, because of precordial pain and malaise, three daysafter eating a bread. Physical examination was unremarkable. The electrocardiogram showed diffuse upward STsegment.A chest radiography showed a foreign body (a pin) in the topography of the esophagus. Esophagoscopywas performed and the pin was removed, with improvement of the patient.Keywords: Precordial pain; Pericarditis; Foreign body; Esophageal trauma; Electrocardiogram; EsophagoscopyDOI: 10.3329/jom.v11i2.5474J MEDICINE 2010; 11 : 200-201
Abstracts from BSM Conference 2010
Authors: Editor The
Published: July 2010

DOI: 10.3329/jom.v11i2.5482J MEDICINE 2010; 11 : 216-232
A Different Independence Day Celebration
Authors: Editor The
Published: July 2010

DOI: 10.3329/jom.v11i2.5484J MEDICINE 2010; 11 : 234