bluuebunny/crossref_metadata_2025 huggingface dataset:
Properly Executed Underbalanced Drilling Technology Adds Reserves and Enhances Ultimate Recovery
Authors: Babajan Salar , Qutob Hani
Published: June 2009

The current world petroleum industry situation is that: ➢Exploration is difficult and costs are increasing.➢The majority of hydrocarbons being exploited today are found in existing pressure depleted or complex and lower quality reservoirs➢Current oil prices are at their highest

Thus, world circumstances have forced today's petroleum industry to rethink both its operating methods and technologies aiming at improving recovery and reducing cost. It is believed that adoption of new technologies is the most important factor in adding reserves, enhancing recovery, reducing cost and increasing revenue. Underbalanced drilling technology is now seen as the way to achieve these objectives.

Introduction

Underbalanced Drilling – UBD main objectives are: ➢Preventing formation damage and improving Reservoir Benefits.➢Improving Drilling Performance & Preventing Conventional Drilling Problems.

This paper discusses in details the reservoir benefits part of underbalanced drilling technology.

What is Underbalanced Drilling?

Underbalanced Drilling is the intentional reduction of the drilling fluid density causing the hydrostatic pressure in a well bore to be lower than the pore pressure within a formation thereby permitting reservoir fluids to be produced while drilling. Underbalanced Drilling benefits the reservoir by simply adding reserves through: ➢Discovery of new zones➢Reducing formation damage and increasing intra-zone contribution➢Lowering abandonment increasing well drainage area➢Accessing challenging reservoirs➢Providing real time reservoir evaluation / characterization.

Although UBD has many advantages, it is not a magic potion for all fields, wells or drilling problems. Poor execution and planning would result in an over-enthusiastic misapplication of the technology, and possibly failure. Several real results and case studies will be presented and discussed in this paper.
Applying New Systematic and Dynamic UBD Procedures to Prevent Formation Damage, Wellbore Collapse and Improve Oil production in Hassi Massoud Field
Authors: Berkat Ali , Kartobi Khelil , Mazouzi Amine , Dhina Okba , Qutob Hani , Barakat Naiem , Grayson Fudge , Marei Ayman
Published: June 2009

The Hassi Massoud oil field is the largest of its kind in Algeria. The reservoir was discovered in 1956 and produces from a Cambrian-age at approximately 3400 meters depth. It produces 45°API oil from a thick Cambro-Ordovician sandstone formation.

This sandstone is extremely hard, abrasive and slow to drill. The reservoir is naturally fractured in some parts. Fractures are either open or plugged with materials such as shale, silica, anhydrite, pyrite and bitumen. Porosity is ranging from 6 to 12%. Generally, the permeability is low with a range of less than 1 to more than 100 md in open-fractures layers

Sonatrach introduced Underbalanced Drilling (UBD) primarily in an effort to improve penetration rates. However, all additional benefits obtained from UBD, such as production improvement and reservoir characterization while drilling, will be of an added value.

Well OMPZ553 is the 37th well drilled underbalanced in the Hassi Massoud field. In this well, the focus was on production improvement with minimum formation damage while the increased rate of penetration (ROP) was a secondary benefit. Another objective was the evaluation of production while the well is being drilled. This eliminates the need for expensive post drilling production testing, and also to minimize borehole instability specially when drilling in the R2 section of the drain.

In order to increase the success rate of drilling and completing this well underbalanced, Sonatrach introduced a new systematic and dynamic procedure. The new procedure consists of: Proper UBD candidate screeningCalculating the actual reservoir pressure before UB mode startsCompleting the well in UB mode

This well proved to be the best UB drilled well in Hassi Massoud field in terms of reservoir benefits and characterization. The pre-job UBD candidate screening, feasibility studies and applying the new procedures proved effective in the success of this well.

This paper describes in detail the above procedure and presents the successful application of such procedure to optimize production and enhance the ultimate recovery in the Hassi Massoud field. Lessons learnt and challenges encountered will also be discussed in this paper
Minimum and Mandatory HSE Training Program for All Personnel Working in Onshore Oil Operations, Applicability and HR Impact
Authors: Remisio Luis , El-Farmaoui Mohamad
Published: June 2009

In contrast with what is followed for Offshore Oil Operations the majority of the Onshore Oil Operations in the world do not have a Minimum and Mandatory required HSE training program for all personnel including contractors and subcontractors.

A comparison is drawn between the Minimum and Mandatory HSE Training Programmes applied offshore in developed areas, mainly North Sea and Gulf of Mexico and the benefits that similar programs can bring to the ME onshore oil operations are addressed by estimating the risk reduction and potential economic benefits.

The applicability of such Minimum and Mandatory HSE Training Programs is analyzed against the scenario of heavy utilization of contractors and subcontractors with different approach and standards in HSE training and also the increasing complexity of the onshore oil operations

An estimation of how many lives can potentially be saved by the introduction of such programs is provided in global and generic terms.

The HR Impact, in different aspects, specifically the ones related to HR Management is analyzed assuming the potential introduction of these mandatory HSE training programs.

Specific conclusions and recommendations are issued and the final argument of the need to introduce a Mandatory HSE Card (or passport) to all personnel working in Onshore Oil Operations is put forward as the most effective method to curb the rate of incidents, specially LTI's, Loss Time Injuries and Fatalities.
Field Development Expansion of a Giant Oil Field in Abu Dhabi Using Artificial Islands as Drilling and Production Centers
Authors: Modavi A. , Martin W. W. , Muflehi A. H. , Walters J. V. , Ismail G.
Published: June 2009

The current development plan for the subject field is based on drilling from numerous Well Head Platform Towers (WHPTs). The current production buildup target would require many more new WHPTs and hundreds of kilometers of new pipelines connecting the new and current towers to the field central processing complex and its satellites.

An alternative field development strategy based on a few drilling/production centers (artificial islands and/or large platforms), instead of numerous new WHPTs, will enable: Significant CAPEX reductionCover current or future variations of the subsurface planMitigation of Jack-Up rig availability & cost uncertaintiesFlexibility to capture up-side potentials during field life cycleProvisions for cost-effective/phased facilities installationsEnhanced field operability, at much lower OPEXReduced downtime losses

Islands as drilling/production centers, with land-based rigs further enable: Maximum flexibility for further developmentHonoring current reservoir management guidelines,Low risk (conservative) extended reach drilling
Condition Management as Part of Asset Management
Authors: Panzke Rolf
Published: June 2009

Definitions: Condition Monitoring/Management –Components of asset management condition monitoring regularly records meaningful data and information on the machine status (machines, plants and their components). The focus is on: abrasion, wear and contamination. The device should report its current status in good time before it fails.–Supports "status-based" or "predictive maintenance"–The aim is to make status data of the assets available on a continuous basis–Condition management collects the data and information, coordinates it, creates courses of action and manages the data.–Maintenance–The combination of all technical, administrative and business-management actions during the life cycle of an object in order to preserve it or restore it to such a condition that enables it to continue performing its original task.–Diagnostics–Identification of faults in the assets (machines, systems and their components)–Locating faults/evaluating the cause of faults–Log of individual faults and causes of faults–Asset–Plant components: apparatus, boilers, machines, pipes and process control instruments–The term does not include infrastructure that do not concern the production systems: buildings, roads, rails…–Plant Asset management–Comprises a "health check" of all assets, condition monitoring and diagnostic functions with the associated decision-making aids. In addition, the system predicts the remaining life and suggests appropriate maintenance measures to the user.

Condition management is an important tool of asset management for optimizing production processes with regard to plant operation, capacity, quality, quantity and reproducibility. The crucial thing here is to recognize future requirements and trends of different industrial sectors as well as regional differences. Part of this process is to develop and build up the competence of the suppliers in the individual industrial segments, in complete solutions, partial solutions, but also in individual components and in the support.

The optimization measures depend in part on the application and solution expertise of the vendor. This includes planning competencies and selection of the optimum measured variables, technologies and products/solutions. The factors that are of increasing importance here are intelligent diagnostics information, condition monitoring and its interpretation, based on the experiences from the condition management. It is the task of the supplier to point out to the customer the advantages of additional solutions in special applications in a wide variety of sectors and to present them transparently as part of the system information – from the first initial definition to the final target of process optimization.
Case Histories - Implementation of New Liner Hanger Technology in South Central Venezuela Significantly Improves Operations in Complex Wells
Authors: Jimenez Cesar , Soto Simon , Leon Andrehny , Batocchio Marcelo , Marval Pedro , Schoener-Scott Martin
Published: June 2009

Liners hangers are used in deep drilling operations to eliminate the need to run full strings of casing. Unlike regular casings that are installed back to surface; liners will be terminated downhole at a hang-off point in the last casing. Deploying liner hangers can be very difficult, depending on the wellbore conditions. In many scenarios, the bottomhole assembly (BHA) must be rotated and/or reciprocated in order to set the BHA at the target depth, and conventional liner hanger systems often do not permit tool rotation due to the complex design. Liner-hanger failures ultimately can be the cause for losing the wellbore or a section of the wellbore, which in turn, will result in additional well construction costs to sidetrack and drill another section through the production zone.

This paper will discuss the use of an expandable liner hanger that has a less complicated design that withstands aggressive reaming as well as drilling to depth. This expandable system has no external moving parts such as slips, hydraulic-setting cylinders or separate liner-top packers, which are used in conventional liners. These attributes help mitigate the risks associated with the deployment exercise and the complexity of the completion.

PDVSA embraced this technology to help them optimize operations in their deep wells in which extreme environments, often close to 300°F, with deviations greater than 60 degrees and setting depths of more that 12,000 feet are encountered.

The benefits that have been gain by adopting this technology are:

Optimized capital expenditure Optimized rig-time efficiency (reduced NPT) Avoidance of costly redundant conditioning trips, hanger damage, and premature setting Elimination of external moving parts on hanger assembly (reduced complexity) Reduced rig time Improved reliability and fluid flow No slip damage to supporting casing

Case histories that compare the traditional and expandable liner hanger systems and verify the advantages stated above are presented.
Contracting Basics to Deliver Projects in Today's Supply Market
Authors: Benham Harry , Marijt Jaap
Published: June 2009

The world of project contracting in the oil and gas industry is in a state of flux, with an unprecedented high demand globally for contractor capability at a time of dwindling people and equipment resources. This is leading to seemingly ever-increasing costs, longer schedules and, all too often, inferior quality in the delivered project. The operators are struggling to find the best response to this variable and volatile situation, and a variety of outsourcing initiatives and contracting strategies are being tried and tested. However, we believe getting the basics right in contracting and procurement is now more important than ever.

In many parts of the world during the 80s and 90s, the capital contracting bias of the International Oil Companies (IOCs) and other operators moved towards large Engineering Procurement and Construction (EPC) contracts, with a lump sum reward mechanism. Large engineering firms, in an effort to enlarge their work scopes, started to provide this integrated EPC service, allowing the IOCs to outsource their labour intensive and detailed project management activities. These EPC-lump sum contracts gave contractors a strong incentive to perform well and, driven by fierce competition and a perceived relatively certain business environment, they assumed many of the risks associated with the project execution and delivery, with sharp focus on their own cost performance. The clients saw ‘competitive fixed prices’ being offered to deliver their projects, and this made contractor selection seem relatively straightforward.

With hindsight, the mid to longer-term consequences of this strategic approach were not foreseen or, at least, were underestimated. For IOCs, many assumed a (sometimes false) sense of cost certainty. Independent Project Analysis (IPA) insightfully stated that the lump sum price was generally perceived as a ceiling price, whereas in reality it was no better than a floor from which cost could, and inevitably often did, grow. This was made worse by the total lack of cost transparency to the IOCs, and hence their inability to meaningfully negotiate the commercial terms for repeat projects and standardisation, or to adequately assess variations and claims. EPC outsourcing also reduced the skill base of the IOCs, and thereby their ability to internally manage large projects and their interfaces at a component level.
Tracking Interwell Water Saturation in Pattern Flood Pilots in a Giant Gulf Oil field
Authors: Bhatti Zahid , Al Mansoori Yousof , El Sembawy Saber , Vahrenkamp Volker , Clerc Nicolas , Wilt Michael , Reeder Stacy
Published: June 2009

Peripheral water flooding has been the preferred pressure maintenance tool for many gulf carbonate reservoirs over the past 30 years. Due to uneven sweep and pressure distribution, this technique has given way to pattern floods in several gulf fields. As these new floods are established, it is important to understand the water saturation between wells to properly manage the sweep and recovery. In 2007, ADCO initiated water injection (WI) and WAG pilots to test the recovery strategy. The pilot employs advanced geophysical and modeling tools to measure formation properties at the wells and between wells; this paper discusses the WI pilot.

Among the novel techniques applied is the crosswell electromagnetic method, which measures the interwell resistivity distribution between observation wells at the pilots. Interwell resistivity data can be used to infer the water saturation distribution because of the sharply different electrical resistivity between injected water and oil bearing reservoir rock. By allowing an evaluation of the water distribution long before the injected fronts reach producers or observers, a better and more rapid understanding of the pilot arises from the crosswell electromagnetic technique.

In this paper, we briefly describe the pilot design, describe the detailed geological model and show results from the initial set of baseline and time lapse EM data sets from the water injection pilot. The images highlight the influence of background geological constraints on the flow.
Characterization of Hydraulically-Induced Fracture Network Using Treatment and Microseismic Data in a Tight-Gas Formation: A Geomechanical Approach
Authors: Xu Wenyue , Calvez Joël Le , Thiercelin Marc
Published: June 2009

Large amount of gas are being produced from unconventional tight-gas sand reservoirs (e.g., Cotton Valley Fm., Lobo Fm., Taylor Sand Fm. and, Wilcox Fm., etc.) and shale gas-bearing formations (e.g, Barnett, Fayetteville, Marcellus, Woodford, etc.). These plays are partly technology driven and partly economics driven. Modern well log evaluation techniques and completion methods are required to yield economic wells. In some cases microseismic monitoring campaigns are performed in these various low permeability environments to improve the understanding of the induced fracture network and to go beyond the simple assumption of a symmetric bi-wing fracture system.

To better characterize the induced fracture network, a semi-analytical pseudo 3-D geomechanical model was developed based on considerations of the conservation of injected fluid mass and the mechanic interactions both between fractures and injected fluid as well as among the fractures. The hydraulically stimulated volume is represented by a horizontally expanding ellipse containing a simplified fracture network consisting of two sets of vertical planar fractures perpendicular to one another. This model provides a mathematically-equivalent description of the process of hydraulic fracture propagation and the characteristics of the induced fractures.

Using microseismic datasets obtained during hydraulic treatments in several tight formations together with measured wellbore pressure and treatment parameters as the input, the modeling analysis yields information of the induced fracture network including fracture spacing and associated confining stress contrast. The results indicate a vertically contained developing fracture network with anisotropic spacing and moderate confining stress contrast. The fracture network extension toward the maximum horizontal stress is however limited. This information is then used as the input of the model to carry out forward simulations and provide detailed information of time-dependent fracture propagation including front location, fluid pressure, fracture width, induced porosity and permeability.
Application of Relative Location Technique from Surface Arrays to Microseismicity Induced by Shale Fracturing
Authors: Hulsey B. J. , Eisner Leo , Thornton Michael , Jurick Dana
Published: June 2009

A matched filter technique that uses cross-correlation and migration of the recorded waveforms has been successfully used to relatively locate microseismic events. In addition to producing consistent relative locations, the matched filter corrects for radiation pattern effects and near-surface structure. The relative locations produced using this methodology were compared with a proprietary, direct location method. The new results produce a solution set that reveals two parallel trends of microseismic events which are interpreted as 1500' long fracture zones approximately 100' wide. We observed asymmetric fracture growth and re-fracturing of the previously stimulated zones. Time correspondence of the observed evolution of seismic events with engineering pump curve data reveals approximate linear growth rates of several feet per minute and possible proppant placement along the induced fractures.
Verification of Flare Line Flows and Pipeline Deposit Measurement Using Non-Intrusive Radioisotope Technology
Authors: Hood Tony
Published: June 2009

Introduction

Over the past forty years a range of services have been available to thepetrochemical and oil & gas industries to investigate the performance oftheir process systems. The various services offered involve the use ofradioactive sealed sources and radioactive unsealed sources, also known astracers, to provide a rapid and detailed on-line assessment of the performanceof process systems. These techniques effectively ‘look’ inside vesselsand pipes to identify their contents and measure their process conditions.

This paper focuses on a selected area of the technology as applied topipelines, but more specifically to Flow Rate Verification in Flare Lines and, more generally Pipeline Deposit Measurement in any pipeline.

Basics of Radioisotope Technology

There are four main types of radioactivity. These are alpha particles, betaparticles, neutrons, and gamma electromagnetic radiation. Alpha and Betaemissions have limited use in industrial applications, as they are very weaklypenetrating and thus cannot be detected through a steel wall (see Fig.1). Neutrons have a very specific use for diagnostic purposes and can beused to determine the presence and location of hydrogenous liquids within aprocess system. Electromagnetic gamma radiation is the most common formof radioactivity used for carrying out on-stream, non-intrusive investigationsas the radiation emitted is able to penetrate and pass through matter, such assteel and insulation, allowing its detection at the outside walls of a processsystem.

Gamma radioisotopes are used in two fundamental physical forms:Sealed sourcesUnsealed sources (otherwise known as tracers)

A sealed source consists of a small pellet of a radioisotope that is sealedwithin a steel case. Sealed sources can be used to scan through a pipe toidentify such things as lining integrity, density of liquid present, presenceof fluid or gas slugging, solids build-up and other process anomalies.
Pilot Scale Facility to Determine Gaseous Emissions from Livestock Slurry during Storage
Authors: Petersen Søren O. , Skov Morten , Drøscher Per , Adamsen Anders P. S.
Published: June 2009

Livestock production is a growing source of air pollution, locally and to the wider environment. Improved livestock manure management has the potential to reduce environmental impacts, but there is a need for methodologies to precisely quantify emissions. This paper describes and evaluates a novel storage facility for livestock slurry consisting of eight 6.5‐m3 cylindrical units. The stores may be equipped with airtight covers and ventilated during storage or during measurement only. Each store has eight air inlets (160 mm diameter) and a single outlet in the cover connected to a main ventilation duct. The stores can also be used as static enclosures. Ventilation can be regulated within the range of 50 to 250 m3 h−1 A gas sampling line enables sampling of odorants using automatic thermal desorption tubes, ammonia using acid traps, and greenhouse gases using gas sampling bags (pooled samples) or a syringe (time point samples). Complete recovery of CH4 independent of ventilation rate was demonstrated. Vertical profiles of CO2 and CH4 above the slurry surface with and without ventilation and mixing of the headspace indicated methane oxidation activity in the surface crust. p‐Cresol and 4‐ethyl phenol emission from pig slurry was identified by GC‐MS analysis of odor collected on adsorption tubes. Ammonia emissions between 0 and 166 mg N m−2 h−1 were observed during storage of pig slurry with and without surface crust and cover. A comparison of pooled and averaged time point measurements of CO2, CH4, and N2O indicated that pooled samples account for the diurnal variations under realistic storage conditions.
Heavy Metal Contamination from Electronic Waste Recycling at Guiyu, Southeastern China
Authors: Guo Yan , Huang Changjiang , Zhang Hong , Dong Qiaoxiang
Published: June 2009

This study evaluated the effect of electronic waste (e‐waste) recycling activities at a regional center, Guiyu, Guangdong, China on heavy metal pollution in the surrounding waterway system. Surface water and sediment collected from the Lianjiang River and its tributaries were analyzed for concentrations of Cu, Pb, Ni, Cd, Hg, and As. Spatially, heavy metals in water and sediment samples decreased downstream of Lianjiang River from Guiyu to the estuary at Haimen Bay. Temporally, heavy metal concentrations in the surface water were high in the rainy season and low in the dry season. In particular, concentrations of Cu from surface water in the Guiyu area were 2.4 to 131 times the reference background concentration, followed in descending order by Ni, Cd, Pb, Hg, and As. However, when compared with China's Environmental Quality Standard, Cd was considered the most harmful element, followed by Hg, Pb, and Cu. Concentrations of Cu in sediment samples in the Guiyu area were 3.2 to 429 times the reference background concentration, followed by Ni, Hg, Pb, Cd, and As. Our findings suggested that high concentrations of heavy metal observed in Guiyu, Lianjiang River and the Haimen Bay could be attributed to the direct effects of e‐waste recycling in Guiyu.
Fertilizer Application Timing Influences Greenhouse Gas Fluxes Over a Growing Season
Authors: Phillips Rebecca L. , Tanaka Donald L. , Archer David W. , Hanson Jon D.
Published: June 2009

Microbial production and consumption of greenhouse gases (GHG) is influenced by temperature and nutrients, especially during the first few weeks after agricultural fertilization. The effect of fertilization on GHG fluxes should occur during and shortly after application, yet data indicating how application timing affects both GHG fluxes and crop yields during a growing season are lacking. We designed a replicated (n= 5) field experiment to test for the short‐term effect of fertilizer application timing on fluxes of methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O) over a growing season in the northern Great Plains. Each 0.30‐ha plot was planted to maize (Zea maysL.) and treated similarly with the exception of fertilizer timing: five plots were fertilized with urea in early spring (1 April) and five plots were fertilized with urea in late spring (13 May). We hypothesized time‐integrated fluxes over a growing season would be greater for the late‐spring treatment, resulting in a greater net GHG flux, as compared to the early‐spring treatment. Data collected on 59 dates and integrated over a 5‐mo time course indicated CO2fluxes were greater (P< 0.0001) and CH4fluxes were lower (P< 0.05) for soils fertilized in late spring. Net GHG flux was also significantly affected by treatment, with 0.84 ± 0.11 kg CO2equivalents m−2for early spring and 1.04 ± 0.13 kg CO2equivalents m−2for late spring. Nitrous oxide fluxes, however, were similar for both treatments. Results indicate fertilizer application timing influences net GHG emissions in dryland cropping systems.
Intravascular Ultrasound (IVUS): A Potential Arthroscopic Tool for Quantitative Assessment of Articular Cartilage
Authors: Huang Yan-Ping , Zheng Yong-Ping
Published: June 2009

Conventional ultrasound examination of the articular cartilage performed externally on the body surface around the joint has limited accuracy due to the inadequacy in frequency used. In contrast to this, minimally invasive arthroscopy-based ultrasound with adequately high frequency may be a better alternative to assess the cartilage. Up to date, no special ultrasound transducer for imaging the cartilage in arthroscopic use has been designed. In this study, we introduced the intravascular ultrasound (IVUS) for this purpose. An IVUS system with a catheter-based probe (Ø ≈ 1mm) was used to measure the thickness and surface acoustical reflection of the bovine patellar articular cartilagein vitrobefore and after degeneration induced by enzyme treatments. Similar measurement was performed using another high frequency ultrasound system (Vevo) with a probe of much larger size and the results were compared between the two systems. The thickness measured using IVUS was highly correlated (r = 0.985, p < 0.001) with that obtained by Vevo. Thickness and surface reflection amplitude measured using IVUS on the enzymatically digested articular cartilage showed changes similar to those obtained by Vevo, which were expectedly consistent with previous investigations. IVUS can be potentially used for the quantitative assessment of articular cartilage, with its ready-to-use arthroscopic feature.
Effect of Hemodialysis, Coronary Artery Disease and Diabetes on Cardiac Troponin T: A Prospective Survey Over One Year
Authors: Mongeon François-Pierre , Dorais Marc , Lorier Jacques Le , Froment Daniel , Letendre Élaine , Rinfret Stéphane
Published: June 2009

Background:

Limited data is available about the effects of hemodialysis sessions, coronary artery disease (CAD), and diabetes on serum cardiac troponin T (cTnT) levels in patients with end-stage renal disease (ESRD).

Objectives:

To test whether hemodialysis could be associated with an increase in cTnT concentration. To evaluate if coronary artery disease (CAD) or diabetes are associated with higher cTnT levels in ESRD.

Methods:

Serum cTnT levels were measured immediately before and after dialysis 3 times over 1 year (0, 6, and 12 months).

Results:

A total of 100 ESRD patients without acute coronary syndrome (mean age of 58.5 years, 34% with diabetes, and 37% with CAD) gave 267 pre-dialysis and 260 post-dialysis blood samples. The mean (standard deviation) pre-dialysis cTnT levels were 0.06 (0.12), 0.05 (0.06), and 0.07 (0.07) mcg/L at 0, 6, and 12 months, respectively. The post-dialysis cTnT levels were similar on average. Among 259 samples with cTnT measured both before and after dialysis, 79 (30.5%) showed a decrease in serum cTnT, 97 (37.5%) showed an increase and 83 (32%) showed no change following dialysis. Mean cTnT was higher in CAD than in non-CAD patients. We observed no significant difference in mean cTnT levels between diabetic and non-diabetic patients.

Conclusions:

cTnT levels were not affected by individual hemodialysis sessions, and remained stable around 0.06 mcg/L over a 1-year period in ESRD patients. Random cTnT levels were higher in stable CAD patients undergoing hemodialysis.
Planetary-Scale Vortical Structures in the Conducting Atmosphere
Authors: Khantadze MA.G. , Jandieri G.V. , Ishimaru A. , Jandieri V.G.
Published: June 2009

The problem of generation and existence of large-scale vortices in the ionosphere is analyzed in this paper. Some exact solutions of the magneto-hydrodynamic (MHD) equations have been found and new invariants have been constructed allowing to descover mechanisms of generation of large-scale vortices and planetary waves in the electroconducting atmosphere under the action of non-conservative Coriolis and Ampere forces.
Quantitative Assessment of Improvement with Single Corticosteroid Injection in Thumb CMC Joint Osteoarthritis?
Authors: Khan Munir , Waseem Mohammad , Raza Ali , Derham Damjana
Published: June 2009

We present a unique prospective study to estimate the median sustained stage-related improvement in pain and hand function in patients with trapezio-metacarpal joint osteoarthritis after administration of a single corticosteroid injection. Response to the corticosteroid injection was assessed using Disability of Arm Shoulder and Hand (DASH) and Visual Analogue Scale (VAS) pain scores. Self assessment scores revealed a reduction in pain and improvement in hand function. All patients reported a significant improvement in pain and hand function (p≤ 0.05), regardless of the disease stage. Additionally, we observed a marked difference in the duration of improvement in hand function between early and late stages of the disease (p= 0.0046). In conclusion, it is possible to predict the period of symptomatic improvement at each of the four radiological stages of the disease. This would allow the treating clinician to judge the outcome of treatment with reasonable accuracy.
Observations of Coyote‐Cat Interactions
Authors: GRUBBS SHANNON E. , KRAUSMAN PAUL R.
Published: June 2009

ABSTRACT Coyotes (Canis latrans) pose a risk to domestic cats (Felis catus). We captured, radiocollared, and tracked 8 coyotes from November 2005 to February 2006 for 790 hours in Tucson, Arizona, USA. We observed 36 coyote‐cat interactions; 19 resulted in coyotes killing cats. Most cats were killed in residential areas from 2200 hours to 0500 hours during the pup‐rearing season. Single coyotes were as effective killing cats as were groups (>1) of coyotes. Documented cases of predators killing cats could encourage cat owners to keep their cats indoors and assist wildlife managers in addressing urban wildlife issues.
Habitat Use by Female Mallards in the Lower Mississippi Alluvial Valley
Authors: DAVIS BRUCE E. , AFTON ALAN D. , COX ROBERT R.
Published: June 2009

ABSTRACT  Mallard (Anas platyrhynchos) populations in the lower Mississippi Alluvial Valley (LMAV), USA, historically averaged 1.6 million and represented the largest concentrations of wintering mallards in North America. Effective management of this wintering population requires current information on use of habitats. Accordingly, we employed radiotelemetry techniques to assess proportional use of habitats by female mallards during winters 2004–2005 and 2005–2006. We divided winters into 4 time periods defined by hunting seasons (FIRST, SPLIT, SECOND, and POST) and recorded diurnal and nocturnal locations. We examined variations in proportional use of habitats and use of areas closed to hunting due to effects of age (immature or ad), winter (2004–2005 or 2005–2006), time period (SECOND or POST), individual female, and all potential interactions of these effects, using locations recorded during the latter 2 time periods. We found that diurnal and nocturnal proportional use of habitats varied inconsistently among time periods and winters. Mean proportional use of forested wetlands ranged from 0.475 to 0.816 and from 0.428 to 0.764 during diurnal and nocturnal sampling periods, respectively. Diurnal proportional use of areas closed to hunting varied inconsistently among time periods and winters. Mean proportional use of areas closed to hunting ranged from 0.183 to 0.423 during diurnal sampling periods. Nocturnal use of areas closed to hunting varied inconsistently among female ages and time periods and among female ages and winters. Mean proportional use of areas closed to hunting ranged from 0.211 to 0.445 during nocturnal sampling periods. Our research suggests that forested wetlands in the LMAV provide important wintering habitats for female mallards; continued restoration and establishment of these habitats should benefit female mallards.
Vocal Individuality of Great Gray Owls in the Sierra Nevada
Authors: ROGNAN CAMERON B. , SZEWCZAK JOSEPH M. , MORRISON MICHAEL L.
Published: June 2009

ABSTRACT  The cryptic plumage and nocturnal nature of the great gray owl (Strix nebulosa) make it difficult to study in its densely forested habitat. We investigated whether the vocalizations of individual great gray owls could be distinguished and used as a tool for population survey and monitoring. We recorded 312 territorial calls produced by 14 male and 11 female great gray owls between March and July 2006 and 2007 in the Sierra Nevada range of California, USA. We recorded 19 owls on multiple occasions within a season and 8 owls between seasons. We extracted 17 frequency and 15 temporal variables from the sonograms of each call. Discriminant analysis selected 9 variables and classified 92.8% of calls to the correct individual within a season; 71.4% of calls were classified to the correct individual between seasons. Our results indicate that territorial calls could be used to monitor individual great gray owls for both short‐ and long‐term studies. Vocal individuality could be useful as a noninvasive method to improve census estimates and yield information on site fidelity, turnover rates, seasonal movements, and behavioral traits of great gray owls.
Factors Influencing Reporting and Harvest Probabilities in North American Geese
Authors: ZIMMERMAN GUTHRIE S. , MOSER TIMOTHY J. , KENDALL WILLIAM L. , DOHERTY PAUL F. , WHITE GARY C. , CASWELL DALE F.
Published: June 2009

ABSTRACT  We assessed variation in reporting probabilities of standard bands among species, populations, harvest locations, and size classes of North American geese to enable estimation of unbiased harvest probabilities. We included reward (US$10, $20, $30, $50, or $100) and control ($0) banded geese from 16 recognized goose populations of 4 species: Canada (Branta canadensis), cackling (B. hutchinsii), Ross's (Chen rossii), and snow geese (C. caerulescens). We incorporated spatially explicit direct recoveries and live recaptures into a multinomial model to estimate reporting, harvest, and band‐retention probabilities. We compared various models for estimating harvest probabilities at country (United States vs. Canada), flyway (5 administrative regions), and harvest area (i.e., flyways divided into northern and southern sections) scales. Mean reporting probability of standard bands was 0.73 (95% CI = 0.69–0.77). Point estimates of reporting probabilities for goose populations or spatial units varied from 0.52 to 0.93, but confidence intervals for individual estimates overlapped and model selection indicated that models with species, population, or spatial effects were less parsimonious than those without these effects. Our estimates were similar to recently reported estimates for mallards (Anas platyrhynchos). We provide current harvest probability estimates for these populations using our direct measures of reporting probability, improving the accuracy of previous estimates obtained from recovery probabilities alone. Goose managers and researchers throughout North America can use our reporting probabilities to correct recovery probabilities estimated from standard banding operations for deriving spatially explicit harvest probabilities.
Spatial Ecology of Raccoons Related to Cattle and Bovine Tuberculosis in Northeastern Michigan
Authors: ATWOOD TODD C. , DELIBERTO THOMAS J. , SMITH HOLLY J. , STEVENSON JUSTIN S. , VERCAUTEREN KURT C.
Published: June 2009

ABSTRACT In 1995,Mycobacterium bovis, the causative bacterium of bovine tuberculosis (bTB), was detected in 5 beef cattle operations in Alcona County, Michigan, USA. In accordance with Federal law, the operations were depopulated to prevent the spread of bTB. Subsequent wildlife surveillance programs identified high prevalence ofM. bovisin mesocarnivores, including raccoons (Procyon lotor), which suggested that raccoons may be complicit in vectoring the pathogen among livestock operations. Our goal was to develop an empirical basis for generating hypotheses about the likelihood for raccoons to mediate the transmission of bTB to livestock. We found intersexual differences in scale‐dependent resource selection and probability of spatial interaction that, under certain circumstances, may form the foundation for a sex‐bias in disease transmission. Spatial dispersion of mixed‐forest patches facilitated overlap of adjacent males, whereas female overlap zones included pastures. Within overlap zones, probabilities of interaction for male‐male and male‐female dyads were greater than for female‐female dyads, although we documented an elevated likelihood of spatial interaction between raccoons and livestock around cattle‐feeding troughs and water sources, regardless of sex. Partial regressions generated by linear models indicated that distance between nearest‐neighbor mixed‐forest patches explained most of this observed variation. These results supported our prediction that forest patches juxtaposed with anthropogenic features fostered social tolerance between males and, thus, facilitated spatial interaction and exploitation of anthropogenic features. In raccoons, sex and landscape composition influenced pathogen transmission potential. We suggest that livestock producers locate livestock feeding and watering features away from forest patches to mitigate future outbreaks of bTB in endemic areas.
Evidence of Alaskan Trumpeter Swan Population Growth Using Bayesian Hierarchical Models
Authors: SCHMIDT JOSHUA H. , LINDBERG MARK S. , JOHNSON DEVIN S. , CONANT BRUCE , KING JAMES
Published: June 2009

ABSTRACT Alaska (USA) contains a large proportion of the breeding population of trumpeter swans (Cygnus buccinator) in the United States. However, tracking population trends in Alaska trumpeter swans is complicated by variables such as an increase in survey effort over time, periodic surveys (1968 and every 5 yr after 1975), and missing data. We therefore constructed Bayesian hierarchical negative binomial models to account for nuisance variables and to estimate population size of trumpeter swans using aerial survey data from all known breeding habitats in Alaska, 1968–2005. We also performed an augmented analysis, where we entered zeroes for missing data. This approach differed from the standard (nonaugmented) analysis where we generated estimates for missing data through simulation. We estimated that adult swan populations in Alaska increased at an average rate of 5.9% annually (95% credibility interval = 5.2–6.6%) and cygnet production increased at 5.3% annually (95% credibility interval = 2.2–8.0%). We also found evidence that cygnet production exhibited higher rates of increase at higher latitudes in later years, which may be a response to warmer spring temperatures. Augmented analyses always produced higher swan population estimates than the nonaugmented estimates and likely overestimate true population abundance. Our results provide evidence that trumpeter swan populations are increasing in Alaska, especially at northern latitudes. Changes in population size and distribution could negatively affect tundra swans (Cygnus columbianus) breeding in Alaska, and biologists should monitor these interactions. We recommend using nonaugmented Bayesian hierarchical analyses to estimate wildlife populations when missing survey data occur.
Deer Carcass Decomposition and Potential Scavenger Exposure to Chronic Wasting Disease
Authors: JENNELLE CHRISTOPHER S. , SAMUEL MICHAEL D. , NOLDEN CHERRIE A. , BERKLEY ELIZABETH A.
Published: June 2009

ABSTRACT  Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy afflicting the Cervidae family in North America, causing neurodegeneration and ultimately death. Although there are no reports of natural cross‐species transmission of CWD to noncervids, infected deer carcasses pose a potential risk of CWD exposure for other animals. We placed 40 disease‐free white‐tailed deer (Odocoileus virginianus) carcasses and 10 gut piles in the CWD‐affected area of Wisconsin (USA) from September to April in 2003 through 2005. We used photos from remotely operated cameras to characterize scavenger visitation and relative activity. To evaluate factors driving the rate of carcass removal (decomposition), we used Kaplan‐Meier survival analysis and a generalized linear mixed model. We recorded 14 species of scavenging mammals (6 visiting species) and 14 species of scavenging birds (8 visiting species). Prominent scavengers included American crows (Corvus brachyrhynchos), raccoons (Procyon lotor), and Virginia opossums (Didelphis virginiana). We found no evidence that deer consumed conspecific remains, although they visited gut piles more often than carcasses relative to temporal availability in the environment. Domestic dogs, cats, and cows either scavenged or visited carcass sites, which could lead to human exposure to CWD. Deer carcasses persisted for 18 days to 101 days depending on the season and year, whereas gut piles lasted for 3 days. Habitat did not influence carcass decomposition, but mammalian and avian scavenger activity and higher temperatures were positively associated with faster removal. Infected deer carcasses or gut piles can serve as potential sources of CWD prions to a variety of scavengers. In areas where surveillance for CWD exposure is practical, management agencies should consider strategies for testing primary scavengers of deer carcass material.
Habitat Use by Sonoran Desert Tortoises
Authors: ZYLSTRA ERIN R. , STEIDL ROBERT J.
Published: June 2009

ABSTRACT  The distribution of desert tortoises (Gopherus agassizii) spans a wide range of biotic and abiotic conditions in the southwestern United States and northwestern Mexico, with physical and behavioral differences distinguishing tortoises inhabiting the Mojave Desert from those inhabiting the Sonoran Desert. Relative to tortoise populations in the Mojave Desert, populations in the Sonoran Desert have not been well‐studied. To assess how habitat use of desert tortoises in the Sonoran Desert was influenced by topography, vegetation, geomorphology, and soil, we surveyed 40 randomly located 3‐ha sites for presence of adult tortoises within a site‐occupancy framework. We modeled both occupancy and detection probability as a function of environmental features, and compared those results with a logistic regression model that assumed detection probability was equal to 1. Results from both approaches agreed, suggesting that habitat selection of tortoises in the Sonoran Desert was influenced primarily by topographic and geomorphologic features rather than by vegetation. Specifically, tortoises were more likely to occupy sites that were steep (we detected tortoises on 29% of sites with mean slope <5° and 92% of sites with mean slope >15°) and predominantly east‐facing (53% of sites with <5% of site facing E and 92% of sites with >20% facing E), and less likely to occupy north‐facing slopes (100% of sites with <10% of site facing N and 14% of sites with >60% facing N). Our results contrast with patterns of habitat use in the Mojave Desert where tortoises primarily occupy valley bottoms. Habitat use of tortoises in Sonoran and Mojave Desert populations differ considerably, contributing to the mounting body of evidence suggesting that these geographically distinct populations may represent separate species.
A New Digital Relaying Scheme for Parallel Transmission Line
Authors: Bhalja Bhavesh , Maheshwari Rudra Prakash , Parikh Urmil B.
Published: June 2009

This paper presents a scheme for the protection of parallel transmission line having two different configurations (geographical locations). In the proposed scheme, the six line currents at a common end of a parallel line or three line currents at a separate end of a parallel line are decomposed using wavelet packet transform (WPT) in order to derive the operating quantities for relay operation. The proposed scheme provides stability against close-in faults, more sensitivity towards high resistance faults and reliability for discriminating in-zone and out-zones faults during complete loss of generation at one of the buses. When the conventional relay, without an intuitive directional element, fails to trip for a remote end fault located in the vicinity of remote bus, the proposed method solves the said problem and also avoids the voltage signal used in conventional relays. Furthermore, the suggested scheme completely avoids the requirement of a distance algorithm as a backup protection in case of the disconnection of one line (due to maintenance or fault). Moreover, the proposed scheme analyzes solves the problem of simultaneous same phase fault on parallel lines. To validate the proposed scheme, numerous computer simulations have been carried out on realistic data of part of the Indian 400 kV power transmission system network.
Two-dimensional diffusion model for the biopolymers dynamics at nanometer scale
Authors: Paun Viorel
Published: June 2009

In this paper the driven transport of linear polymers through a nanopore is presented. Biopolymer physical behavior in an external electric field is modeled and its motion is simulated using the Langevin impulse integrator method. Within fairly large limits, the polymer translocation time is inversely proportional with the electric field intensity and directly proportional with the polymer chain length.
Editorial for Vol.5(1)
Authors: Editors The
Published: June 2009

doi: 10.3126/jfl.v5i1.1972Journal of Forest and Livelihood 5(1) February, 2006