bluuebunny/crossref_metadata_2025 huggingface dataset:
Increased Morning Brain Natriuretic Peptide Levels in Children With Nocturnal Enuresis and Sleep- Disordered Breathing: A Community-Based Study
Authors: Capdevila Oscar Sans , Crabtree Valerie McLaughlin , Kheirandish-Gozal Leila , Gozal David
Published: May 2008

INTRODUCTION. Habitual snoring and obstructive sleep apnea have been associated with bed-wetting in children, and effective obstructive sleep apnea treatment may improve enuresis.

OBJECTIVES. The purpose of this work was to assess whether habitual snoring is associated with increased incidence of enuresis and whether severity of obstructive sleep apnea correlates with enuretic frequency and to evaluate brain natriuretic peptide levels.

METHODS. Parental surveys of 5- to 7-year-old children were reviewed for habitual snoring and enuresis. Enuresis was also assessed in a cohort of 378 children with habitual snoring undergoing overnight polysomnographic evaluation, and brain natriuretic peptide plasma levels were determined in 20 children with obstructive sleep apnea, 20 with habitual snoring without obstructive sleep apnea, and 20 nonsnoring children, matched for enuresis.

RESULTS. There were 17646 surveys completed (50.6% boys; 18.3% black). A total of 1976 (11.2%) of these children were habitual snoring (53% boys; 25.2% black). A total of 531 habitual snoring children also had enuresis (26.9%), with a predominant representation of boys (472 boys [87.5%]). Among the 15670 nonsnoring children, enuresis was reported in 1821 children (11.6%), of whom 88.8% were boys. However, enuresis among 378 children with habitual snoring did not correlate with the magnitude of sleep respiratory disturbances. Indeed, enuresis was reported in 33 of 149 children with obstructive sleep apnea (obstructive apnea hypopnea index: >2 per hour of total sleep time; 53% boys) as compared with 36 habitual snoring children with enuresis (62% boys) and obstructive apnea hypopnea index <2 per hour of total sleep time. Brain natriuretic peptide levels were elevated among children with enuresis and were marginally increased among children with obstructive sleep apnea.

CONCLUSIONS. Habitual snoring is associated with increased prevalence of enuresis, and brain natriuretic peptide levels are increased in enuretic children with further increases with obstructive sleep apnea. However, the prevalence of enuresis is not modified by severity of sleep disturbance. Even mild increases in sleep pressure because of habitual snoring may raise the arousal threshold and promote enuresis, particularly among prone children, that is, those with elevated brain natriuretic peptide levels.
Pediatric Invasive Aspergillosis: A Multicenter Retrospective Analysis of 139 Contemporary Cases
Authors: Burgos Ana , Zaoutis Theoklis E. , Dvorak Christopher C. , Hoffman Jill A. , Knapp Katherine M. , Nania Joseph J. , Prasad Priya , Steinbach William J.
Published: May 2008

OBJECTIVE. Invasive aspergillosis is a major cause of morbidity and mortality in immunocompromised children. Invasive aspergillosis has been well characterized in adults; however, the incidence and analysis of risk factors, diagnostic tools, treatments, and outcomes have not been well described for a large cohort of pediatric patients.

METHODS. We conducted the largest retrospective review of contemporary cases of proven and probable pediatric invasive aspergillosis diagnosed at 6 major medical centers (January 1, 2000, to July 1, 2005).

RESULTS. Aspergillus fumigatus was the species most frequently recovered (52.8%) for the 139 patients analyzed. The majority of the children had a malignancy with or without hematopoietic stem cell transplant. Significant risk factors that impacted survival were immunosuppressive therapies and allogeneic stem cell transplant. The most common clinical site of invasive aspergillosis was the lungs (59%), and the most frequent diagnostic radiologic finding was nodules (34.6%). Only 2.2% of children showed the air crescent sign, 11% demonstrated the halo sign, and cavitation was seen in 24.5% of patients. Before the diagnosis of invasive aspergillosis, 43.1% of patients received fluconazole, and 39.2% received liposomal amphotericin B. After the diagnosis of invasive aspergillosis, 57% were treated with a lipid formulation of amphotericin B; however, 45.8% received ≥3 concomitant antifungal agents. Analysis did not show superiority of any 1 antifungal related to overall mortality. A total of 52.5% (73 of 139) died during treatment for invasive aspergillosis. Of all the interventions implemented, surgery was the only independent predictor of survival.

CONCLUSIONS. Our analyses revealed common findings between adult and pediatric invasive aspergillosis. However, one key difference is diagnostic radiologic findings. Unlike adults, children frequently do not manifest cavitation or the air crescent or halo signs, and this can significantly impact diagnosis. Immune reconstitution, rather than specific antifungal therapy, was found to be the best predictor of survival.
Unbound Bilirubin Concentration is Associated With Abnormal Automated Auditory Brainstem Response for Jaundiced Newborns
Authors: Ahlfors Charles E. , Parker Anne E.
Published: May 2008

OBJECTIVE. This study was conducted to determine whether incidental jaundice affects automated auditory brainstem response results.

METHODS. We reviewed the medical charts of jaundiced newborns of ≥34 weeks of gestation who underwent automated auditory brainstem response testing within 4 hours of plasma total bilirubin concentration and unbound bilirubin concentration measurements. We tested the hypothesis that the likelihood of abnormal automated auditory brainstem response results would increase as total bilirubin and unbound bilirubin concentrations increased.

RESULTS. Forty-four infants with proximate total bilirubin concentration, unbound bilirubin concentration, and automated auditory brainstem response measurements were identified, and 4 (9%) had bilateral refer automated auditory brainstem response results. The mean total bilirubin concentration of 21.4 mg/dL (SD: 4.0 mg/dL; range: 14.4–29.5 mg/dL) for the 40 infants with bilateral pass automated auditory brainstem response results was not significantly different from that of 23.0 mg/dL (range: 14.9–33.1 mg/dL) for the 4 infants with bilateral refer automated auditory brainstem response results. However, the mean unbound bilirubin concentration of 1.32 μg/dL (range: 0.22–2.99 μg/dL) for the 40 infants with bilateral pass results was significantly lower than the mean of 2.62 μg/dL (range: 0.88–4.41 μg/dL) for the 4 infants with bilateral refer results. Logistic regression showed that increasing unbound bilirubin concentrations but not increasing total bilirubin concentrations were associated with of bilateral refer automated auditory brainstem response results.

CONCLUSIONS. The probability of bilateral refer automated auditory brainstem response results increases significantly with increasing unbound bilirubin concentrations but not with increasing total bilirubin concentrations. Because unbound bilirubin concentrations are also more closely correlated with bilirubin neurotoxicity than are total bilirubin concentrations, bilateral refer automated auditory brainstem response results for jaundiced newborns may indicate increased risk of bilirubin neurotoxicity, in addition to the possibility of congenital deafness.
Prenatal Exposure to Maternal Infections and Epilepsy in Childhood: A Population-Based Cohort Study
Authors: Sun Yuelian , Vestergaard Mogens , Christensen Jakob , Nahmias André J. , Olsen Jørn
Published: May 2008

OBJECTIVE. We estimated the association between prenatal exposure to maternal infections and the subsequent risk for epilepsy in childhood.

METHODS. We included 90619 singletons who were born between September 1997 and June 2003 in the Danish National Birth Cohort and followed them up to December 2005. Information on maternal infections during pregnancy (cystitis, pyelonephritis, diarrhea, coughs lasting >1 week, vaginal yeast infection, genital herpes, venereal warts, and herpes labialis) was prospectively reported by mothers in 2 computer-assisted telephone interviews in early and midgestation; information on maternal cystitis and pyelonephritis during late period of pregnancy was also collected in a third interview after birth. Children who received a diagnosis of epilepsy as inpatients or outpatients were retrieved from the Danish National Hospital Register. We identified 646 children with a diagnosis of epilepsy during up to 8 years of follow-up time. Cox proportional hazards regression models were used to estimate incidence rate ratio and 95% confidence interval.

RESULTS. Children who were exposed to maternal cystitis, pyelonephritis, diarrhea, coughs, and/or vaginal yeast infection some maternal infections in prenatal life had an increased risk for epilepsy. Coughs lasting >1 week were associated with an increased risk for epilepsy only in the first year of life, as was vaginal yeast infection only in children who were born preterm. These associations remained unchanged for children without cerebral palsy, congenital malformation, or a low Apgar score at 5 minutes.

CONCLUSIONS. Prenatal exposure to some maternal infections was associated with an increased risk for epilepsy in childhood.
National Young-Driver Survey: Teen Perspective and Experience With Factors That Affect Driving Safety
Authors: Ginsburg Kenneth R. , Winston Flaura K. , Senserrick Teresa M. , García-España Felipe , Kinsman Sara , Quistberg D. Alex , Ross James G. , Elliott Michael R.
Published: May 2008

BACKGROUND. Motor vehicle crashes are the leading cause of fatality and acquired disability in adolescents. Young, inexperienced drivers are overrepresented in crashes.

OBJECTIVE. Our goal was to explore the adolescent perspective on driving safety to provide a better understanding of factors that influence safety and teenagers' exposure to driving hazards.

METHODS. Adolescents generated, prioritized, and explained their viewpoint by using the teen-centered method. These viewpoints were obtained from a school-based nationally representative survey of 9th-, 10th-, and 11th-graders (N = 5665) from 68 high schools, conducted in spring 2006, that included teen-generated items. The main outcome measures were rating of risk and prevalence of witnessing driving hazards.

RESULTS. Drinking while driving was ranked as the greatest hazard (87% of the respondents reported that it made a lot of difference), although only 12% witnessed it often. Ranked next as dangers while driving were text-messaging, racing, impairment from marijuana, and road rage. Sixty percent viewed inexperience as a significant hazard, although only 15% reported seeing it often. Cell phone use was viewed as a significant hazard by 28%, although 57% witnessed it frequently. Only 10% viewed peer passengers as hazardous, but 64% frequently observed them. Distracting peer behaviors, among other distractions, were viewed as more dangerous. Subpopulations varied in the degree they perceived hazards. For example, black and Hispanic adolescents viewed substance use while driving as less hazardous than did white adolescents but witnessed it more frequently.

CONCLUSIONS. Adolescents generally understand the danger of intoxicated driving. However, some groups need to better recognize this hazard. Distractions take teenagers' focus off the road, but not all are viewed as hazardous. Although inexperience is the key factor that interacts with other conditions to cause crashes, adolescents do not recognize what merits experience. Future research is needed to explore how to help teens become safer drivers and how to make clinicians, families, and communities more effective in setting, promoting, and monitoring safety standards.
Decreased Respiratory Compliance in Infants Less Than or Equal to 32 Weeks' Gestation, Delivered More Than 7 Days After Antenatal Steroid Therapy
Authors: McEvoy Cindy , Schilling Diane , Spitale Patricia , Peters Dawn , O'Malley Jean , Durand Manuel
Published: May 2008

OBJECTIVES. Our objective was to compare the pulmonary function (respiratory compliance) of infants who were ≤32 weeks' gestation and delivered >7 days after a single course of antenatal steroids versus infants who were delivered 1 to 7 days after a single course of antenatal steroids.

METHODS. A prospective cohort study of respiratory system compliance was conducted of infants ≤32 weeks' gestation within 72 hours of life and before surfactant therapy if needed. The study (remote) group was composed of infants who were treated with antenatal steroids >7 days before delivery and the comparison group (ideal group) of matched infants who were treated with antenatal steroids 1 to 7 days before delivery. Respiratory system compliance was measured with the single-breath occlusion technique.

RESULTS. Twenty-eight remotely treated infants and 28 ideally treated infants were studied. The remote group had a significantly lower respiratory system compliance per kilogram and total respiratory system compliance when compared with the ideal antenatal steroids group. Within the remote group, infants who received antenatal steroids 8 to 14 days (n = 10) before delivery had a significantly higher respiratory system compliance and a trend to less surfactant need (10% vs 33%) as compared with infants who received antenatal steroids >14 days (n = 18) before delivery.

CONCLUSIONS. Infants who were ≤32 weeks' gestation and remotely treated with antenatal steroids (average 21 days) had a significantly lower respiratory compliance compared with matched infants who were ideally treated with antenatal steroids. We speculate that the lower respiratory system compliance may reflect the dissipation of beneficial effects of antenatal steroids on pulmonary function when delivery occurs >7 days after therapy and particularly when therapy is >14 days before delivery.
Reevaluating the Safety Profile of Pediatrics: A Comparison of Computerized Adverse Drug Event Surveillance and Voluntary Reporting in the Pediatric Environment
Authors: Ferranti Jeffrey , Horvath Monica M. , Cozart Heidi , Whitehurst Julie , Eckstrand Julie
Published: May 2008

OBJECTIVES. Children are at exceptionally high risk for adverse drug events. At Duke University Hospital, computerized adverse drug event surveillance and voluntary safety reporting systems work synergistically to identify adverse drug events. Here we identify the most deleterious drug classes to pediatric inpatients and determine which detection methodology provides the greatest opportunity to reduce harm.

PATIENTS AND METHODS. We evaluated all of the medication-related events detected by our computerized surveillance and safety reporting systems over a 1-year period for Duke University Hospital pediatric inpatients. Events from both systems were scored for severity and assigned a drug event category. Surveillance events were additionally scored for causality.

RESULTS. A total of 849 medication-related reports were entered into the safety reporting system, and 93 caused patient harm, resulting in an adverse drug event rate of 1.8 events per 1000 pediatric patient-days. Seventy eight of the 1537 medication-related events detected by surveillance resulted in patient harm, giving a rate of 1.6 events per 1000 patient-days. The most common events identified by the safety reporting system were failures in the medication use process (26.9%), drug omissions (16.1%), and dose- or rate-related events (12.9%). The most frequent adverse drug event surveillance categories were nephrotoxins (20.7%), narcotics and benzodiazepines (19.3%), and hypoglycemia (11.5%). Most voluntarily reported events originated in ICUs (72.0%), whereas surveillance events were split evenly across intensive and general care. There was little overlap between methodologies.

CONCLUSIONS. The epidemiology of pediatric adverse drug events is best addressed by using voluntary reporting in tandem with other strategies, such as computerized surveillance and targeted chart review. Although voluntary reporting excels at identifying administration errors, surveillance excels at detecting adverse drug events caused by high-risk medications and identifies evolving conditions that may provoke imminent patient harm. Surveillance underperformed in pediatrics when compared with adult detection rates, suggesting that tailored rules may be necessary for a robust pediatric adverse drug event surveillance system.
Role of the School Nurse in Providing School Health Services
Authors:   Council on School Health
Published: May 2008

The school nurse has a crucial role in the seamless provision of comprehensive health services to children and youth. Increasing numbers of students enter schools with chronic health conditions that require management during the school day. This policy statement describes for pediatricians the role of the school nurse in serving as a team member in providing preventive services, early identification of problems, interventions, and referrals to foster health and educational success. To optimally care for children, preparation, ongoing education, and appropriate staffing levels of school nurses are important factors for success. Recommendations are offered to facilitate the working relationship between the school nurse and the child's medical home. This statement has been endorsed by the National Association of School Nurses.
Complementation of Habitats for Bonneville Cutthroat Trout in Watersheds Influenced by Beavers, Livestock, and Drought
Authors: White Seth M. , Rahel Frank J.
Published: May 2008

Multiple age‐classes of Bonneville cutthroat trout Oncorhynchus clarkii utah throughout two Rocky Mountain watersheds were influenced by interactions among geomorphology, land use, activity by beavers Castor canadensis, and drought. Age‐0 trout were present in a limited portion of the watersheds, and their distribution became increasingly restricted as drought conditions developed over a 3‐year period. The Coal Creek watershed (including Huff Creek) produced the most age‐0 trout in the first 2 years of the drought, lacked beaver activity, and was affected by land use, suggesting that spawning habitat was determined by geomorphology rather than land use or beaver activity. However, the high abundance of age‐0 cutthroat trout in Huff Creek did not result in a high abundance of juvenile and older age‐classes of fish in subsequent years, most likely because of the lack of complementary habitats providing refuge for older fish. A nearby watershed and its major stream, Water Canyon, had less spawning habitat and produced fewer age‐0 fish during the first 2 years of the study but had more trout in the juvenile and adult age‐classes, most likely because of a higher degree of habitat complementation. In Water Canyon, less‐intense livestock grazing and the presence of beavers allowed for the development of pools and woody riparian vegetation that provided cover for older trout. Water Canyon was also the only stream to produce age‐0 trout during the most severe year of drought, suggesting that streams with more natural habitat may provide a spawning refuge during low‐flow conditions that occur periodically in the region. These results demonstrate that habitat complementation is important for the coexistence of multiple age‐classes of fish and that the adjacency of spawning habitat and refugia is crucial for the persistence of fish in the face of environmental stress associated with drought.
Temporal and Spatial Variability in the Migration Patterns of Juvenile and Subadult Bull Trout in Northeastern Oregon
Authors: Homel Kristen , Budy Phaedra
Published: May 2008

Conservation planning for threatened bull troutSalvelinus confluentusrequires the identification of temporal and spatial movement patterns to better understand the patch size and connectivity requirements of different behavioral strategies (e.g., resident and migratory) and life stages (e.g., juvenile and adult). Although these patterns have been identified for adults, less is known about the movement patterns of juvenile and subadult bull trout. Thus, we evaluated the movement patterns and abiotic and biotic cues associated with migration timing of fluvial juvenile and subadult (150‐300 mm) bull trout in the South Fork Walla Walla River, northeastern Oregon. From 2002 to 2005, we tagged 1,636 individuals with passive integrated transponder (PIT) tags and monitored subsequent movements (within the study area) and migrations (exiting of the study area) by PIT tag detection at antennae and active detection during the mark‐recapture sampling season. Juveniles and subadults exhibited downstream movements and migrations throughout the year; movement and migration activity peaked in August, and migrations occurred predominantly at night (94%). We modeled migration timing in response to abiotic and biotic cues and observed distinct seasonal patterns in migration timing that were associated with changes in minimum temperature. However, the seasonal models based on temperature explained only 23‐35% of the variation in migration timing, suggesting the influence of additional variables. Based on the temporal and spatial continuum of movement observed here, we believe that management must address the occupancy of multiple habitat types and migration corridors throughout the year.
Validity of Steady-State Upscaling Techniques
Authors: Jonoud S. , Jackson M. D.
Published: May 2008

Steady-state upscaling techniques are attractive because they are quick and simple to implement; unlike dynamic methods, there is no need for fine-grid simulation, and the upscaled properties are not case dependent. They are based on the assumption that either capillary forces (capillary equilibrium limit, CL) or viscous forces (viscous limit, VL) dominate flow. However, the reservoir conditions for which these assumptions are valid have not been clearly defined. It is generally supposed that the CL method is valid at "low" flow rates over "small" lengthscales, while the VL method is valid at "high" flow rates over "large" lengthscales. These qualitative criteria are difficult to properly apply and can be easily violated, yielding significant errors in predicted reservoir performance.

We have identified a comprehensive suite of dimensionless groups which can be used to define the validity of steady-state methods. The groups account for the effect of heterogeneity, as well as the other parameters which control the balance between capillary and viscous forces. Numerical simulations have been used to identify the range of values for these groups over which steady-state methods are valid. Our results yield a practical set of quantitative criteria which can be used to determine the validity of steady-state upscaling methods for a wide range of geological models. They capture the effects of capillary trapping and are valid regardless of fluid mobility, wettability, or endpoint saturation.

We test our criteria against three realistic models of small- to intermediate-scale geological heterogeneity. We find that the criteria do a good job of predicting the range of validity for each method, and are conservative in all cases, suggesting that if they are met, then steady-state upscaling techniques can be applied with confidence and may still be valid for slightly less restrictive conditions. However, in the models investigated, we find that the validity of the CL method is restricted to very low flow rates, which are unlikely to be encountered in most production scenarios. This is because the CL method overestimates the amount of capillary trapping. In general, VL upscaling is valid over a much more reasonable range of reservoir flow rates.
Compositional Modeling of Oil-Based-Mud-Filtrate Cleanup During Wireline Formation Tester Sampling
Authors: Alpak Faruk O. , Elshahawi Hani , Hashem Mohamed , Mullins Oliver
Published: May 2008

Miscible oil-based-mud (OBM) filtrate contamination poses a major challenge to the acquisition of representative fluid samples using wireline formation testers (WFTs). A sound understanding of the OBM-filtrate cleanup process and identification of first-order impact parameters are of paramount importance for the design of next-generation WFT probes that can operate in OBM-filtrate environments with enhanced efficiency.

We have constructed a numerical model for OBM-filtrate cleanup using an equation-of-state (EOS) compositional fluid-flow simulator. The numerical cleanup model honors the physics of multicomponent-fluid flow and the thermodynamics of phase behavior. Simulation results exhibit close agreement with analytical predictions and with field data for the time dependence of contamination during sampling. First-order impact parameters were identified through a sensitivity study using the numerical model. It has been found that the clean-up function is predominantly governed by permeability anisotropy, porosity, cleanup flowrate, viscosity ratio, depth of invasion, distance between the WFT probe and a sealing boundary, formation thickness, and wellbore radius. A response-surface-based contamination model (RSCM) was developed using the above-described simulation investment with additional runs. RSCM constitutes a rapid approximate model and can serve as a prejob-planning or real-time-analysis tool. Our simulation and rapid-modeling results compare well with empirical observations made in the field. In particular, the rate of change of miscible contamination with time has been found to vary between t0.3 and t0.6, with t0.45 representing a good average value. For the first time, modeling has been shown to give essentially the same results as empirical observations.
Effect of Fracture Compressibility on Gas-in-Place Calculations of Stress-Sensitive Naturally Fractured Reservoirs
Authors: Aguilera Roberto
Published: May 2008

A tank material-balance equation for gas reservoirs has been written, taking into account the effective compressibility of matrix and fractures.

The method has direct application to stress-sensitive naturally fractured reservoirs (NFRs). Under some conditions, ignoring the effect of fracture compressibility (Cf) can lead to overestimating the volume of original gas in place with a crossplot of p/z vs. cumulative gas production (Gp). The equation presented in this paper has been developed to overcome that weakness. The use of the tank material balance is illustrated with an example.

It is concluded that fracture compressibility can play an important role in the calculation of gas in place in stress-sensitive NFRs.

The subject matter is significant because, historically, formation and water compressibilities have been neglected when carrying out material-balance calculations for conventional gas reservoirs. This assumes that these compressibilities are negligible compared to that of gas. The assumption implies that the reservoir strata are static. When water influx is ignored, the assumption leads to a straight line in a crossplot of p/z vs. Gp. However, this study shows that in those instances in which fracture compressibility is large, such assumptions can lead to significant error.
Use of the NMR Diffusivity Log To Identify and Quantify Oil and Water in Carbonate Formations
Authors: Rosa D. Di , Gyllensten A. , Chen S. , Li W. , Georgi D. , Tauk R.
Published: May 2008

This paper reports on a successful example of using the 2D NMR technique for determining oil-water contact (OWC) in difficult carbonate environments. An NMR diffusion-based interpretation method was used to identify oil, water, and transition zones and to quantify oil saturation in a limestone reservoir. Hydrocarbon typing and saturation determination from NMR logging usually require high contrasts of intrinsic or apparent relaxation times, dif-fusivity, or both. Many carbonate reservoirs in the Middle East contain large pores, which together with the low relaxivity of carbonates, create long T1 and T2 times for water. Furthermore, because light oil has a long relaxation time, there is little contrast in T2 or polarization between water and oil. When these reservoirs contain very light or high-GOR oils, the diffusivity contrast between oil and water is also less pronounced. Hence, it is difficult to distinguish between the oil and water signals with most NMR hydrocarbon-typing techniques. The example shows that a diffusion log constructed from 2D NMR interpretation works well even for marginal diffusion-contrast cases. In addition, a modification to the Coates permeability model is presented that is applicable to carbonate formations having partially connected vugs.
Quantifying Resources for the Surmont Lease with 2D Mapping and Multivariate Statistics
Authors: Ren Weishan , Deutsch Clayton V. , Garner David L. , Wheeler T. J. , Richy Jean-François , Mus Emmanuel
Published: May 2008

The McMurray formation consists of heterogeneous Cretaceous-bitumen-saturated sands. The reservoirs are thick and laterally extensive in the main fairways. Many commercial projects are in the early stages of development. Resources too deep to mine are considering steam assisted gravity drainage (SAGD) (Butler 1991). Detailed high-resolution 3D geostatistical modeling is useful for individual well-pair or pad flow simulation, but is neither practical nor necessary for resource assessment across large areas.

A methodology for resource assessment is developed from a geostatistical study on the Surmont lease. The uncertainty in more than 30 correlated variables is calculated on a dense 2D grid using all available information including wells, seismic, and geologic trends. The correlation structure between the variables is modeled under a multivariate Gaussian model. The local distributions of uncertainty have been checked with cross validation and with more than 100 new wells drilled during the last two drilling seasons. Resource uncertainty across the entire lease area and a number of arbitrary development areas is derived from the 2D maps of uncertainty. A combined P -field/LU simulation approach is used; the global uncertainty is consistent with the local uncertainty.
A New Method for Estimating Average Reservoir Pressure: The Muskat Plot Revisited
Authors: Crump J. G. , Hite R. H.
Published: May 2008

This paper describes a new method for estimating average reservoir pressure from long-pressure-buildup data on the basis of the classical Muskat plot. Current methods for estimating average reservoir pressure require a priori information about the reservoir and assume homogeneous reservoir properties or use empirical extrapolation techniques.

The new method applies to heterogeneous reservoirs and requires no information about reservoir or fluid properties. The idea of the method is to estimate from the pressure derivative the first few eigenvalues of the pressure-transient decay modes. These values are characteristic of the reservoir and fluid properties, but not of the pressure history or well location in the reservoir. The smallest eigenvalue is used to extrapolate the long-time behavior of the transient to estimate the final reservoir pressure. The second eigenvalue can be used to estimate the quality of the estimate.

Numerical tests of the method show that it estimates average reservoir pressure accurately, even when the reservoir is heterogeneous or when partial-flow barriers are present. Examples with real data show that the behavior predicted by the theory is actually observed.

We expect the method to have value in reservoir limits testing, in making consistent estimates of average reservoir pressure from permanent downhole gauges, and in characterizing complex reservoirs.
Production Data Analysis of Coalbed-Methane Wells
Authors: Clarkson C. R. , Jordan C. L. , Gierhart R. R. , Seidle J. P.
Published: May 2008

Recent advances in production data analysis (PDA) techniques have greatly assisted engineers in extracting meaningful reservoir and stimulation information from well-production and flowing-pressure data. Application of these techniques to coalbed-methane (CBM) reservoirs requires the unique coal storage and transport properties to be accounted for. In recent work, the authors [ex. Clarkson et al. (2007a) and Jordan et al. (2006)] and others [ex. Gerami et al. (2007)] have demonstrated how new techniques such as the flowing material balance (FMB) and production type curves may be adapted to account for CBM storage mechanisms (i.e., adsorption), but, to date, the focus has been on relatively simple CBM reservoir behavior such as single-phase (gas) reservoirs with static effective permeability.

The major contribution of the current work is the adaptation of modern PDA techniques (by use of modified material balance time/pseudotime and pseudopressure definitions) to analyze producing wells completed in CBM reservoirs exhibiting several possible flow characteristics: single-phase flow of gas in dry CBM reservoirs, single-phase flow of water (in undersaturated reservoirs), and two-phase (gas and water) flow (in saturated reservoirs). The latter reservoir type commonly exhibits effective permeability changes during depletion (because of relative and/or absolute permeability changes) and changing gas composition caused by relative adsorption effects, both of which have been accounted for in the current work. Specifically, the FMB technique is modified to include several complex CBM reservoir characteristics, and production type curves are applied to some scenarios. Although dry-CBM-well analysis was covered previously [ex. Clarkson et al. (2007a)], we will also discuss FMB development in these reservoirs for completeness.

Several synthetic and field examples are given to demonstrate how FMB, type-curve analysis, and analytical simulation can be used in parallel to provide a particularly useful data-analysis toolset and workflow. These techniques were used successfully to extract quantitative reservoir information from single- and two-phase CBM-simulated and field-production pressure data. The PDA techniques developed for two-phase CBM require further evaluation, however.
Hydrocarbon Compositional Gradient Revealed by In-Situ Optical Spectroscopy
Authors: Fujisawa Go , Betancourt Soraya S. , Mullins Oliver C. , Torgersen Torleif , O'Keefe Michael , Terabayashi Toru , Dong Chengli , Eriksen Kåre Otto
Published: May 2008

This paper presents a case study of a North Sea appraisal well in which a vertical fluid-composition variation, missed by a conventional pressure-gradient-analysis method, was observed in situ in real time by a new fluid-composition analyzer using visible near-infrared (NIR) spectroscopy. For optimal oil production, assessing the spatial variation of fluid properties is as vital as assessing the spatial variation of formation properties.

Conventional wireline triple-combination measurements showed that the interval of interest was uniform and free of noticeable impermeable layers. A resistivity log showed an approximate oil/water contact (OWC). Wireline pressure testing identified three different pressure gradients corresponding to gas, oil, and water, all in hydraulic communication. However, the pressure testing did not indicate a gradient in hydrocarbon composition. Fluid was sampled and analyzed in real time by a wireline fluid-sampling-analyzing tool string that included the fluid-composition analyzer. This tool analyzes petroleum fluid and gives concentrations for four group compositions (C1, C2–C5, C6+, and CO2), gas/oil ratio (GOR), and qualitative information regarding heavy-end content and stock-tank crude density. The analyzer showed that the hydrocarbon fluid in an oil-bearing zone was not vertically homogeneous but, instead, had a vertical variation. The samples captured by the wireline sampling tool were sent to a laboratory for compositional analysis that confirmed the variation determined by the downhole analysis. Both results identified the heterogeneity of hydrocarbon fluid in the interval.

This paper also briefly covers the measurement principle of the analyzer and discusses the impacts and benefits brought about by the new technology. The concept of flexible fluid sampling is particularly important because it enables operators to make sampling decisions on the basis of real-time fluid-analysis results rather than a predetermined job plan.
Partial Probabilistic Addition: A Practical Approach for Aggregating Gas Resources
Authors: Delfiner Pierre , Barrier Robert
Published: May 2008

The portfolio of gas sources to supply a liquefied-natural-gas (LNG) project may involve many diverse fields, each with its range of uncertainty and degree of maturity. For project approval, it is necessary to aggregate the reserves/resources of all these fields into project-level representative numbers, either deterministic or probabilistic.

Arithmetic addition of all low estimates (1P or P90) and all high estimates (3P or P10) is known to overstate the range of uncertainty. On the other hand, independent probabilistic addition tends to produce unrealistically narrow ranges. The correct answer would be obtained by using correlated addition, but this requires the estimation of all correlations between field-resource estimates.

This paper presents a simplified and pragmatic approach, partial probabilistic addition. A hierarchy of "resource containers" is defined from individual reservoirs to total project level, and resources are aggregated from bottom upward using either arithmetic or probabilistic addition—whichever is more appropriate. This amounts to setting weak correlations to 0 and strong correlations to 1. Expert opinion is solicited only concerning the strength of dependencies, rather than being asked to specify elusive correlation coefficients.

The validity of the approach is investigated by applying partial probabilistic addition to a synthetic portfolio of fields with the same log-normal size distribution. The study indicates the feasibility of estimating a global P90 with a controlled error, whereas for a P10, the error can become quite large. The method is then discussed using a real LNG case study.

Partial probabilistic addition is a practical method. It is easy to understand and to explain. It can be summarized in a single table where a color code indicates how its value was calculated for each cell. These features facilitate technical interchange and quality control, which are key to reducing as much as possible the degree of arbitrariness inherent in the modeling of dependencies.
Revisiting Reservoir Flood-Surveillance Methods Using Streamlines
Authors: Batycky Rod P. , Thiele Marco R. , Baker Richard O. , Chugh Shelin H.
Published: May 2008

This paper revisits classic flood-surveillance methods applied to injection/production data and demonstrates how such methods can be improved with streamline-based calculations. Classic methods rely on fixed patterns and geometric-based well-rate allocation factors (WAFs). In this paper, we compare conclusions about pattern performance from classic surveillance calculations to conclusions about pattern performance from a streamline surveillance model using flow-based WAFs. We show that very different conclusions on pattern performance can be reached, depending on which approach is used. We introduce streamline-defined, time-varying injector-centered patterns as the basic pattern unit, with offset producers being those to which the injector is connected. Such patterns give a better measure of an injector's true effectiveness because of the improved estimation of offset oil production compared to fixed, predefined patterns.

In the second part of this paper, we illustrate how to build a relevant streamline-based surveillance model. We compare WAFs and offset oil production computed from much more laborintensive, history-matched flow-simulation models to that from much simpler surveillance models and illustrate the difference with a field example. As long as offset-well rates are a function of neighboring-well rates—as is typical in many waterfloods— capturing first-order flow effects is sufficient to produce a surveillance model that is useful for reservoir-engineering purposes. Properly accounting for well locations, historical rates, gross geological bodies, and major flow barriers is generally sufficient to produce a useful surveillance model that replicates well pairs and total interwell fluxes that are similar to those of more-complex and more-expensive history-matched models. We believe that this similarity arises because historical well rates already mirror reservoir connectivity, and it is well rates that mainly impact how the streamlines connect well pairs.
Apoptosis of ligamentous cells of the cranial cruciate ligament from stable stifle joints of dogs with partial cranial cruciate ligament rupture
Authors: Krayer Magali , Rytz Ulrich , Oevermann Anna , Doherr Marcus G. , Forterre Franck , Zurbriggen Andreas , Spreng David E.
Published: May 2008

Objective—To describe the presence and amount of apoptotic ligamentous cells in different areas of partially ruptured canine cranial cruciate ligaments (prCCLs) and to compare these findings with apoptosis of ligamentous cells in totally ruptured cranial cruciate ligaments (trCCLs).

Animals—20 dogs with prCCLs and 14 dogs with trCCLs.

Procedures—Dogs with prCCLs or trCCLs were admitted to the veterinary hospital for stifle joint treatment. Biopsy specimens of the intact area of prCCLs (group A) and the ruptured area of prCCLs (group B) as well as specimens from trCCLs (group C) were harvested during arthroscopy. Caspase-3 and poly (ADP-ribose) polymerase (PARP) detection were used to detect apoptotic ligamentous cells by immunohistochemistry.

Results—No difference was found in the degree of synovitis or osteophytosis between prCCLs and trCCLs. No difference was found in degenerative changes in ligaments between groups A and B. A substantial amount of apoptotic cells could be found in > 90% of all stained slides. A correlation (rs = 0.71) was found between the number of caspase-3-and PARP-positive cells. No significant difference was found in the amount of apoptotic cells among the 3 groups. No significant correlation could be detected between the degree of synovitis and apoptotic cells or osteophyte production and apoptotic cells.

Conclusions and Clinical Relevance—The lack of difference between the 3 groups indicates that apoptosis could be a factor in the internal disease process leading to CCL rupture and is not primarily a consequence of the acute rupture of the ligament.
Changes in gallbladder volume in healthy dogs after food was withheld for 12 hours followed by ingestion of a meal or a meal containing erythromycin
Authors: Ramstedt Keri L. , Center Sharon A. , Randolph John F. , Yeager Amy E. , Erb Hollis N. , Warner Karen L.
Published: May 2008

Objective—To assess the influence of meal ingestion and orally administered erythromycin on gallbladder volume in dogs.

Animals—22 healthy dogs.

Procedures—Ultrasonographically determined gallbladder dimensions in unsedated dogs were used to calculate volume. Measurements were recorded after food was withheld for 12 hours (time 0) and 15, 30, 45, 60, 90, and 120 minutes after a 100-g meal without (n = 22) or with erythromycin (1.0 mg/kg [7], 2.5 mg/kg [7], and both dosages [8]). Gallbladder ejection fraction represented the percentage of volume change from time 0. Intraday and interday coefficients of variation determined operator repeatability and physiologic variation.

Results—We did not detect significant differences in gallbladder volume per unit of body weight between treatments at time 0 or in ejection fraction percentage within or between treatments. Median time 0 gallbladder volume was 0.6 mL/kg (range, 0.4 to 1.9) but was > 1.0 mL/kg in 3 of 22 (14%) dogs and ≤ 1.0 mL/kg in 19 of 22 (86%) dogs. Twenty dogs achieved an ejection fraction ≥ 25% with at least 1 treatment, but 2 dogs with a gallbladder volume ≤ 1.0 mL/kg at time 0 did not. Intraday and interday coefficients of variation were 18% and 25%, respectively.

Conclusions and Clinical Relevance—Gallbladder volume ≤ 1.0 mL/kg at time 0 and ejection fraction ≥ 25% were typical. No treatment consistently induced greater gallbladder contraction. Dogs with a gallbladder volume > 1.0 mL/kg and ejection fraction < 25% may require a combined meal and erythromycin protocol.
Activity of selected rostral and caudal hyoid muscles in clinically normal horses during strenuous exercise
Authors: Morello Samantha L. , Ducharme Norm G. , Hackett Richard P. , Warnick Lorin D. , Mitchell Lisa M. , Soderholm L. Vince
Published: May 2008

Objective—To determine the phase and quantitate the electromyographic (EMG) activity of the genioglossus, geniohyoideus, hyoepiglotticus, omohyoideus, sternohyoideus, sternothyroideus, and thyrohyoideus muscles of clinically normal horses during strenuous exercise.

Animals—7 clinically normal adult horses (2 Thoroughbreds and 5 Standardbreds).

Procedures—Bipolar electrodes were surgically implanted in the aforementioned muscles, and horses were subjected to an incremental exercise test on a high-speed treadmill. The EMG, heart rate, respiratory rate, and static pharyngeal airway pressures were measured during exercise. The EMG was measured as mean electrical activity (MEA). The MEA values for maximal exercise intensity (13 or 14 m/s) were expressed as a percentage of the MEA measured at an exercise intensity of 6 m/s.

Results—MEA was detected during expiration in the genioglossus, geniohyoideus, sternohyoideus, and thyrohyoideus muscles and during inspiration in the hyoepiglotticus and sternothyroideus muscles. Intensity of the MEA increased significantly with exercise intensity in the genioglossus, geniohyoideus, and hyoepiglotticus muscles. Intensity of the MEA increased significantly in relation to expiratory pharyngeal pressure in the geniohyoideus and hyoepiglotticus muscles.

Conclusions and Clinical Relevance—Once exercise intensity reached 6 m/s, no quantifiable additional increase in muscular activity was detected in the omohyoideus, sternohyoideus, sternothyroideus, and thyrohyoideus muscles. However, muscles that may affect the diameter of the oropharynx (genioglossus and geniohyoideus muscles) or rima glottis (hyoepiglotticus muscle) had activity correlated with the intensity of exercise or expiratory pharyngeal pressures. Activity of the muscles affecting the geometry of the oropharynx may be important in the pathophysiologic processes associated with nasopharyngeal patency.