bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification of contrastive and comparable school neighborhoods for childhood obesity and physical activity research
Authors: Zhang Xingyou , Christoffel Katherine Kaufer , Mason Maryann , Liu Lin 
Published: April 2006

Abstract
The neighborhood social and physical environments are considered significant factors contributing to children's inactive lifestyles, poor eating habits, and high levels of childhood obesity. Understanding of neighborhood environmental profiles is needed to facilitate community-based research and the development and implementation of community prevention and intervention programs. We sought to identify contrastive and comparable districts for childhood obesity and physical activity research studies.
We have applied GIS technology to manipulate multiple data sources to generate objective and quantitative measures of school neighborhood-level characteristics for school-based studies. GIS technology integrated data from multiple sources (land use, traffic, crime, and census tract) and available social and built environment indicators theorized to be associated with childhood obesity and physical activity. We used network analysis and geoprocessing tools within a GIS environment to integrate these data and to generate objective social and physical environment measures for school districts. We applied hierarchical cluster analysis to categorize school district groups according to their neighborhood characteristics. We tested the utility of the area characterizations by using them to select comparable and contrastive schools for two specific studies.

Results

We generated school neighborhood-level social and built environment indicators for all 412 Chicago public elementary school districts. The combination of GIS and cluster analysis allowed us to identify eight school neighborhoods that were contrastive and comparable on parameters of interest (land use and safety) for a childhood obesity and physical activity study.

Conclusion

The combination of GIS and cluster analysis makes it possible to objectively characterize urban neighborhoods and to select comparable and/or contrasting neighborhoods for community-based health studies.
Moderate Hypoxia Influences Excitability and Blocks Dendrotoxin Sensitive K+ Currents in Rat Primary Sensory Neurones
Authors: Gruss Marco , Ettorre Giovanni , Stehr Annette Jana , Henrich Michael , Hempelmann Gunter , Scholz Andreas 
Published: April 2006

Hypoxia alters neuronal function and can lead to neuronal injury or death especially in the central nervous system. But little is known about the effects of hypoxia in neurones of the peripheral nervous system (PNS), which survive longer hypoxic periods. Additionally, people have experienced unpleasant sensations during ischemia which are dedicated to changes in conduction properties or changes in excitability in the PNS. However, the underlying ionic conductances in dorsal root ganglion (DRG) neurones have not been investigated in detail. Therefore we investigated the influence of moderate hypoxia (27.0 ± 1.5 mmHg) on action potentials, excitability and ionic conductances of small neurones in a slice preparation of DRGs of young rats. The neurones responded within a few minutes non-uniformly to moderate hypoxia: changes of excitability could be assigned to decreased outward currents in most of the neurones (77%) whereas a smaller group (23%) displayed increased outward currents in Ringer solution. We were able to attribute most of the reduction in outward-current to a voltage-gated K+ current which activated at potentials positive to −50 mV and was sensitive to 50 nM α-dendrotoxin (DTX). Other toxins that inhibit subtypes of voltage gated K+ channels, such as margatoxin (MgTX), dendrotoxin-K (DTX-K), r-tityustoxin Kα (TsTX-K) and r-agitoxin (AgTX-2) failed to prevent the hypoxia induced reduction. Therefore we could not assign the hypoxia sensitive K+ current to one homomeric KV channel type in sensory neurones. Functionally this K+ current blockade might underlie the increased action potential (AP) duration in these neurones. Altogether these results, might explain the functional impairment of peripheral neurones under moderate hypoxia.
Prolactin Deficiency Is Independently Associated with Reduced Insulin-Like Growth Factor I Status in Severely Growth Hormone-Deficient Adults
Authors: Mukherjee A. , Ryder W. D. J. , Jöstel A. , Shalet S. M. 
Published: April 2006

Abstract
Background: In adult life, considerable overlap in IGF-I status exists between normal and severely GH-deficient (GHD) subjects defined by conventional dynamic testing of GH secretion. IGF-I is not therefore widely viewed as a reliable diagnostic marker for GHD. Recognized factors influencing serum IGF-I level in GHD include age, gender, timing of onset of GHD, and exogenous estrogen therapy, but these do not fully explain GH/IGF-I discordance in severe GHD. The primary structures of prolactin and GH are closely related. Effects of hypoprolactinemia are not well described in humans, but laboratory studies suggest a role for prolactin in hepatic IGF-I release, possibly through a signal transducer and activator of transcription 5 (STAT5) pathway. The purpose of this study was to evaluate a potential contribution of prolactin to IGF-I status in severely GHD adults.
Patients and Methods: Using multiple regression analysis techniques, contributions of the following variables to age-adjusted IGF-I sd scores were evaluated in 162 (85 female) GHD adults: gender, timing of onset of GHD, presence or absence of prolactin deficiency, body mass index, number of additional pituitary deficits, and underlying pathology.
Results: Childhood onset GHD (P &lt; 0.0001) and presence of prolactin deficiency (P &lt; 0.0001) were independently associated with reduced IGF-I status. The contributions of these parameters to IGF-I sd scores were −2.55 and −2.67, respectively. Gender (P = 0.06), body mass index (P = 0.99), number of additional pituitary deficits (P = 0.64), and underlying pathology (P = 0.06) did not significantly influence IGF-I status.
Conclusions: Prolactin deficiency is independently associated with reduced IGF-I status in hypopituitary adults. It is possible that prolactin deficiency is a surrogate for the degree of severity of GHD, implying a GHD paradigm undetected by conventional GH provocative tests; alternatively, it remains plausible that circulating prolactin contributes to IGF-I release in the absence of GH, possibly through a signal transducer and activator of transcription 5 (STAT5) pathway.
Enhanced Peroxidase Activity of Cytochrome c by Phosphate Bilayer Membrane
Authors: Fujita Akio , Senzu Hiroyuki , Kunitake Toyoki , Hamachi Itaru 
Published: April 2006

Abstract
Peroxidase activity of cytochrome c (cyt-c) as measured by oxidation of o-methoxyphenol with H2O2, was enhanced due to binding of cyt-c to a phosphate bilayer membrane. The rate enhancement and the membrane binding were not observed with ammonium and zwitterionic bilayer membranes.
Spectral Characteristics and Molecular Orientation of Azobenzene-Containing Hydrogen-Bond-Mediated Bilayer Membranes
Authors: Kimizuka Nobuo , Kawasaki Takayoshi , Kunitake Toyoki 
Published: April 2006

Abstract
Amphiphilic complexes of complementary hydrogen bond pairs containing an azobenzene chromophore formed bilayer membranes in water. The component orientation and thermal stability of the bilayer were examined by absorption and ICD spectral characteristics of the azobenzene chromophore.
Oxidations of Dihydroxyalkanoates to Vicinal Tricarbonyl Compounds with a 4-BzoTEMPO-Sodium Bromite System or by Indirect Electrolysis Using 4-BzoTEMPO and Bromide Ion
Authors: Inokuchi Tsutomu , Liu Ping , Torii Sigeru 
Published: April 2006

Abstract
An efficient access to vicinal dioxoalkanoates, one of structural elements of potent competitive inhibitors of hydrolytic enzyme, from 2,3-dihydroxyalkanoates has been developed, which features an one-step procedure with a mild oxidizing system using recyclable 2,2,6,6-tetramethylpiperidine-1-oxyl in combination with NaBrO2·3H2O or electrogenerated active bromine species as a real oxidant.
Photocatalytic Reduction of CO2 with Dispersed TiO2/Cu Powder Mixtures in Supercritical CO2
Authors: Mizuno Takayuki , Tsutsumi Hozumi , Ohta Kiyohisa , Saji Akira , Noda Hidetomo 
Published: April 2006

Abstract
CO2 was photocatalytically reduced to formic acid and methanol in supercritical CO2 using TiO2 and metal copper suspensions in the presence of water as hole scavengers. Copper particules covered by oxides films were more active in CO2 than TiO2.
Electrochemical Removal of NO and CH4 from Oxidizing Atmosphere
Authors: Hibino Takashi 
Published: April 2006

Abstract
An electrochemical cell, Pd | YSZ | Pd, was constructed to remove both NO and CH4 from an oxidizing atmosphere. When the direct current was supplied to the cell at 700 °C in the reactant flow containing 1000 ppm NO, 1000 ppm CH4 and an excess amount of O2, NO was reduced to N2 at the cathode, and CH4 was oxidized to COx at the anode.
Permeability, Pore Pressure, and Leakoff-Type Distributions in Rocky Mountain Basins
Authors: Craig David P. , Eberhard Mike J. , Ramurthy Muthukumarappan , Odegard Chad E. , Mullen Rebekah 
Published: April 2006

Summary
The permeability, pore pressure, and leakoff type interpreted from more than 1,200 diagnostic fracture-injection/falloff tests were collected in a database and statistically evaluated for four Rocky Mountain basins. The statistical analysis includes the range of observed permeability and pore pressure and the fracture leakoff type distribution.
The analysis reveals that pressure-dependent leakoff, fracture-tip extension during shut-in, and fracture-height recession during shut-in are the most common leakoff types. Overall, pressure-dependent leakoff, which can be indicative of highly productive fractured reservoirs, is the most common leakoff type in all Rocky Mountain basins. The analysis also shows orders-of-magnitude variation in gas permeability within all basins, with observed gas permeability ranging from less than 0.001 to greater than 0.10 md.
Experimental Design and Analysis Methods for Assessing Volumetric Uncertainties
Authors: Cheong Y. P. , Gupta R. 
Published: April 2006

SummaryExperimental design and analysis (EDA) methods can be used practically to minimize the number of 3D geological models that must be built to capture and assess the significant effects in multiple deterministic (or scenario) modeling. This study investigates the feasibility of EDA methods by using three examples. It includes discussions and guidelines on how to select efficient design matrices by using expert knowledge (the possible effects of an experiment) and a decision tree, and how the experimental response can be fitted accurately with the response surface method to develop a good surrogate equation.
Computation of Capillary Pressure and Global Mobility From Spontaneous Water Imbibition Into Oil-Saturated Rock
Authors: Li Kewen , Horne Roland N. 
Published: April 2006

SummaryAn approach was developed to extract the imbibition capillary pressure and the global mobility data from spontaneous water imbibition tests in oil/water/rock systems. Capillary pressure and global mobility data were calculated using this method with the experimental data of countercurrent spontaneous water imbibition tests in different rocks and at different interfacial tensions. The calculated capillary pressures were consistent with the change in interfacial tension. The oil/water/rock systems with greater interfacial tensions had greater capillary pressures. However, the oil/water/rock systems with greater capillary pressure may not have greater imbibition rate. The calculated values of the global mobility and the imbibition index explain why the oil recovery or the imbibition rate in systems with high interfacial tension was smaller than that in systems with low interfacial tension, which has been considered a paradoxical result for many years.
A Successful Methanol Treatment in a Gas/Condensate Reservoir: Field Application
Authors: Al-Anazi Hamoud A. , Walker Jacob G. , Pope Gary A. , Sharma Mukul M. , Hackney David F. 
Published: April 2006

SummaryA field test was conducted to investigate the effectiveness of methanol as a solvent for removing condensate blockage. On the basis of laboratory results and a single-well numerical simulation, a field test was conducted on a gas well that suffered from gradual productivity decline caused by condensate banking in the Hatter's Pond field in Alabama. The well chosen for treatment was producing 250 MMscf/D of gas with 87 BOPD of condensate. After methanol treatment, both gas- and condensate-production rates increased by a factor of two over the first 4 months and by 50% thereafter.
Downhole Measurement of Methane Content and GOR in Formation Fluid Samples
Authors: Dong Chengli , Hegeman Peter S. , Carnegie Andrew , Elshahawi Hani 
Published: April 2006

Summary
Formation fluid sampling early in the life of a well ensures that vital information is available for timely input to field planning decisions. For example, in subsea wells, flow assurance is a major concern, and formation fluid samples from openhole logging help operators optimize investment in both upstream and downstream facilities.
When a formation fluid sample is taken from a well drilled with oil-based mud (OBM), sample contamination by the OBM filtrate is a critical factor for the accurate measurement of the sample pressure/volume/temperature (PVT) properties. A technique of monitoring sample contamination from OBM filtrate uses optical means to monitor the buildup of both color- and methaneabsorption signals during sampling. The technique provides realtime analysis of sample contamination. Methane detection is essential for condensates and lightly colored crude oils; for such fluids, the color buildup becomes difficult to detect, but the high methane content of these fluids makes possible a reliable methane-based OBM-contamination monitoring algorithm.
Gas/oil ratio (GOR) is an important property of crude oil, and it is a vital input to the design of production facilities. Conventionally, GOR is measured at a PVT laboratory, and it may take many weeks before the laboratory can provide this critical information. In this paper, we describe the development of an in-situ GOR measurement technique, which uses the optical properties of methane and oil components in crude oil. With this technique, GOR can be measured downhole in real time, when the sample is taken, and without requiring phase separation.
Downhole GOR has many advantages over the conventional GOR measurement techniques. It does not require tampering with the sample, which helps the operator maintain the fluid in a single phase during and after sampling. It also can aid in fingerprinting oils from different layers and provides early indications of GOR that can be compared to PVT lab results.
Both the OBM contamination monitoring and the GOR algorithms work well for most crude oils. However, for heavy (dark) oils, the contamination prediction from the methane component and the GOR prediction become unreliable because of the color effect. In this paper, we describe the methodology for downhole GOR measurement, and we provide details of a decolorization technique to remove the color effect of dark oils from the methane, oil, and base channels in a downhole optical fluid analyzer tool. This technique significantly improves real-time contamination monitoring and GOR prediction results for dark oils.
New Findings on Damage Potential, Geochemical Reaction Mechanisms, and Production Enhancement Applications for Citric Acid
Authors: Al-Khaldi M. H. , Nasr-El-Din H. A. , Blauch M. E. , Funkhouser G. P. 
Published: April 2006

Summary
Application of citric acid for damage removal in both clastic and carbonate rocks has historically not received widespread acceptance because of formation damage concerns regarding precipitation of calcium citrate. In addition, usage of citric acid in place of hydrochloric acid has been avoided because of lower bulk carbonate dissolving power relative to hydrochloric acid. However, environmental, safety, and corrosion concerns with using hydrochloric acid have sparked renewed interest in citric acid for stimulation.
This paper reconsiders the use of citric acid as both an additive to conventional hydrochloric acid systems and as a stand-alone acidizing fluid. The paper reviews extensive laboratory work focused on understanding reaction pathways and geochemical precipitation issues, and it takes a new look at paradigms related to the calcium citrate issue.
Laboratory studies performed independently by two research laboratories address two main areas of investigation: (1) Evaluation of potential geochemical reaction paths and precipitation of calcium citrate and (2) mechanisms for generation of preferential etching in two carbonate rock lithotypes. The described mechanism for etching enhances conductivity in a contrasting mode compared to hydrochloric acid.
Findings based on this work provide new insights into the applications, usage, and potential limitations of citric acid. A newly proposed process for downhole reaction is presented. This process differs greatly from long-held paradigms built on a foundation of bench-top experimentation. Factors controlling downhole reactions are disclosed, and the results of core testing and fracture conductivity experiments are presented.
The Role of Cutoffs in Integrated Reservoir Studies
Authors: Worthington Paul F. , Cosentino Luca 
Published: April 2006

SummaryThere have been many different approaches to quantifying cutoffs, with no single method emerging as the definitive basis for delineating net pay. Yet each of these approaches yields a different reservoir model, so it is imperative that cutoffs be fit for purpose (i.e., they are compatible with the reservoir mechanism and with a systematic methodology for the evaluation of hydrocarbons in place and the estimation of ultimate hydrocarbon recovery). These different requirements are accommodated by basing the quantification of cutoffs on reservoir-specific criteria that govern the storage and flow of hydrocarbons. In so doing, particular attention is paid to the relationships between the identification of cutoffs and key elements of the contemporary systemic practice of integrated reservoir studies. The outcome is a structured approach to the use of cutoffs in the estimation of ultimate hydrocarbon recovery. The principal benefits of a properly conditioned set of petrophysical cutoffs are a more exact characterization of the reservoir with a better synergy between the static and dynamic reservoir models, so that an energy company can more fully realize the asset value.
A Comprehensive Skin-Factor Model of Horizontal-Well Completion Performance
Authors: Furui Kenji , Zhu D. , Hill A. D. 
Published: April 2006

SummaryHorizontal wells or laterals are completed as openhole, slotted-liner, cased and perforated, or gravel-pack completions. We have developed a comprehensive skin-factor model to predict the performance of any of these completion types and have calibrated this model with extensive finite-element simulations of flow for a horizontal-well completion. This model can be used to predict the performance of virtually any horizontal-well completion.The new completion skin-factor model accounts for the effects of formation damage, convergent flow to perforations and slots, and flow through slots, with interaction among these effects. To account for formation damage, we extended our previous rigorous model of a damaged horizontal well to include the presence of perforations within, or extending through, the damage zone. The formation damage model is also integrated with the models of slotted-liner performance to model these completions. The model of slotted-or perforated-liner performance is made on the basis of the relationship between pressure drop and flow rate for turbulent flow in these geometries. The slotted-liner model accounts for partial plugging of the slots by grains of formation minerals or precipitates (scale). Turbulence effects are a major part of the apparent skin factor for these completion types.The model shows the recommended conditions to obtain high-productivity (i.e., low skin factor) completions in horizontal wells. In particular, the interactions among damage effects and skin effects caused by perforations or slots are shown to greatly affect horizontal-well completion performance. The models developed can be applied to design optimal completions for horizontal wells or laterals.
Automatic History Matching in a Bayesian Framework, Example Applications
Authors: Zhang Fengjun , Skjervheim Jan Arild , Reynolds A. C. , Oliver D. S. 
Published: April 2006

SummaryThe Bayesian framework allows one to integrate production and static data into an a posteriori probability density function (pdf) for reservoir variables (model parameters). The problem of generating realizations of the reservoir variables for the assessment of uncertainty in reservoir description or predicted reservoir performance then becomes a problem of sampling this a posteriori pdf to obtain a suite of realizations. Generation of a realization by the randomized-maximum-likelihood method requires the minimization of an objective function that includes production-data misfit terms and a model misfit term that arises from a prior model constructed from static data. Minimization of this objective function with an optimization algorithm is equivalent to the automatic history matching of production data, with a prior model constructed from static data providing regularization. Because of the computational cost of computing sensitivity coefficients and the need to solve matrix problems involving the covariance matrix for the prior model, this approach has not been applied to problems in which the number of data and the number of reservoir-model parameters are both large and the forward problem is solved by a conventional finite-difference simulator.In this work, we illustrate that computational efficiency problems can be overcome by using a scaled limited-memory Broyden-Fletcher-Goldfarb-Shanno (LBFGS) algorithm to minimize the objective function and by using approximate computational stencils to approximate the multiplication of a vector by the prior covariance matrix or its inverse. Implementation of the LBFGS method requires only the gradient of the objective function, which can be obtained from a single solution of the adjoint problem; individual sensitivity coefficients are not needed. We apply the overall process to two examples. The first is a true field example in which a realization of log permeabilities at 26,019 gridblocks is generated by the automatic history matching of pressure data, and the second is a pseudofield example that provides a very rough approximation to a North Sea reservoir in which a realization of log permeabilities at 9,750 gridblocks is computed by the automatic history matching of gas/oil ratio (GOR) and pressure data.
Method for Characterizing Secondary and Tertiary Reactions Using Short Reservoir Cores
Authors: Ziauddin Murtaza , Gillard Matthew , Lecerf Bruno , Frenier Wayne , Archibald Iain , Healey Duncan 
Published: April 2006

SummaryA new technique for characterizing secondary and tertiary reactions during sandstone-matrix-stimulation treatments is presented. In the new technique, traditional experiments on short reservoir cores are supplemented with measurement of the effluent-element concentrations, batch-reactor experiments, and geochemical simulations to predict the extent of secondary and tertiary reactions in the reservoir treatment. Alternative methods of characterizing secondary and tertiary reactions, such as those using long core flow tests and laboratory radial-flow setups, are reviewed.The new design technique is used in designing a treatment for a well in the North Sea. Details of how this technique was applied to the treatment design are presented. Post-treatment data from the well showed a successful matrix-treatment design. The production from the well increased by 1,400% immediately after the treatment. The 3-month stabilized production gain was 650%.