Search

We describe the case of Jessica Barnett, an adolescent girl whose repeated episodes of syncope and near-syncope were ascribed to a seizure or anxiety disorder. The correct diagnoses (congenital long QT syndrome; arrythmogenic right ventricular cardiomyopathy) were established by autopsy and genetic studies only after her death at age 17. The perspective of the family is presented, along with an analysis of what went right and what went wrong in Jessica’s diagnostic journey. Key lessons in this case include the value of family as engaged members of the diagnostic team, that a ‘hyperventilation test’ should not be used to exclude cardiac origins of syncope or pre-syncope, and the inherent challenges in the diagnosis of the long QT syndrome.

Barnett Continent Ileal Reservoir is rarely performed in patients with ulcerative colitis who require colectomy. Prepouch ileitis occasionally occurs in patients with ileal pouches. The role of oral mesalamine in the treatment of prepouch ileitis has not been established. We describe a case in which prepouch ileitis in Barnett Continent Ileal Reservoir was successfully treated with oral mesalamine. This is the first case in the literature showing that mesalamine is safe and effective in the treatment of prepouch ileitis in a patient with a continent ileostomy.

The Barnett Shale play in North Texas is one of the largest active onshore shale gas regions in the United States. Over the past two decades, unconventional energy production from shale gas in North Texas has grown rapidly. The energy production peaked in 2012 and has declined since. The city of Denton is located at the edge of the Barnett Shale play and is within the Dallas-Fort Worth metropolitan area. In this paper, we describe a long-term trend study of 84 total non-methane organic carbon (TNMOC) species measured at the Denton Airport South monitoring station, an exurban site. The annual mean TNMOC concentrations measured during 2000–2017 increased by +8.03 ± 12.92 ppb-C/year (+12.75%/year). The year-to-year increase in the mean TNMOC concentrations mirrored the energy production volume changes from natural gas wells and liquid condensate facilities within 2-km from the ambient air quality monitoring station. Concentrations of alkanes increased significantly, especially the natural gas species of ethane, propane, n-butane, and isobutane. The annual variations in the ethane concentrations were similar to changes observed in the natural gas and liquid condensate production from nearby wells. High levels of ethane, a dominant natural gas species, were originating from regions with a higher density of gas wells within close proximity of the monitoring site. In contrast, the concentrations of alkene and aromatic species have declined during the study period as a result of decreases from traditional urban emission sources. However, the trend in benzene, a carcinogenic aromatic species found in vehicular and natural gas emissions, and xylene concentrations were similar to the n-alkane trend, suggesting the influence of energy production activities on key ambient aromatic compounds.

Natural gas produced from shale formations in the United States over the past decade have altered the oil and gas industry remarkably. The Barnett shale was at the forefront of the shale gas revolution in the United States and was considered to be the highest producing natural gas field in the United States until 2012, yielding the top producer spot to the Marcellus shale. Due to the uncertainty regarding the accurate determination of Estimated Ultimate Recoverable (EUR) in shale gas reservoirs, this paper aims to assess EUR values for the Barnett shale using empirical decline curve methods like the Arp's hyperbolic, Modified Arp's hyperbolic and Doung's method. In addition, we investigated the economic viability of wells over time in the Barnett under various probabilities of success. Throughout this paper, reference is made to two key publications where a similar work was carried out for various shale plays in the United States, including the Barnett shale – though only the Arp's hyperbolic decline was employed. The dataset in this paper consisted of more horizontal wells from covering more counties within the Barnett shale compared to other similar studies. We conclude that either the Arp's hyperbolic or Doung's method can be used to forecast EUR in the Barnett shale as only marginal differences were observed. This is on the basis that production history exceeds 10 months (a maximum of 80 months production history was used). We also obtained reliable and conservative estimates of EUR compared to previous studies.

Ronald Barnett’s modern classic Realizing the University in an Age of Supercomplexity (published December 1999), has had a crucial impact internationally on the field of Higher Education research and develop- ment since the book was published now nearly 20 years ago. Bridging an academic oeuvre across almost 30 years with close to 30 published volumes, Realizing the University in an Age of Supercomplexity plays an important role in the development and transformation of Barnett’s social theory of Higher Education into a social philosophy of Higher Education. In the book Barnett performs an important move from a focus on knowledge and epistemology to a focus on being and ontol- ogy in relation to Higher Education practices. Barnett shifts his fundamental perspective and view on the relation between universities and the wider society from one of caution and worry to a perspective of hope and vision that fully embraces the future of Higher Education. This way, Realizing the University in an Age of Supercomplexity has not only paved the way for Barnett’s own devel- opment of a social philosophy of Higher Education, but also contributed invaluably to the rise and maturing of philosophy of Higher Education as a research field in its own right.

Despite potential advantages in spatial/temporal coverage compared to measurement studies, few modeling studies have been conducted of non-methane air pollutants associated with natural gas. The objective of this study was to model volatile organic compound (VOC) and criteria pollutants from natural gas production, considering multiple well pads under different terrain conditions, using the Texas Barnett Shale as a case study. Primary criteria pollutants from compressor engines (carbon monoxide, CO; nitrogen oxides, NOx; particulate matter, PM10; sulfur dioxide, SO2) were modeled using AERMOD, along with benzene as a VOC with potential worst health impacts, from condensate tanks, fugitive sources, and compressor engines. Modeling was conducted for level, moderate, and strong sloping terrain, with well pad densities of 1.4–1.9 well pads/km2, exemplifying common maximum densities in the Barnett Shale. In most cases, well pads were far enough away from each other that maxima at individual well pads were not influenced by other pads. When the same well pad arrangement and emission rates were modeled in different terrain types, strong sloping terrain gave the highest maximum concentrations. For the well pad arrangements and emission scenarios modeled, CO, NOx, PM10, and SO2 maximum concentrations were less than the 1-h National Ambient Air Quality Standards (NAAQS). Benzene concentrations, however, exceeded the 1-h effect screening level (ESL) for level and strong sloped terrain, and the annual ESL for all terrain types. The maximum benzene emissions modeled likely represent a reasonable worst-case for the Barnett Shale but underestimate emissions for areas with wetter gas.

Greenhouse gas emissions mitigation requires understanding the dominant processes controlling fluxes of these trace gases at increasingly finer spatial and temporal scales. Trace gas fluxes can be estimated using a variety of approaches that translate observed atmospheric species mole fractions into fluxes or emission rates, often identifying the spatial and temporal characteristics of the emission sources as well. Meteorological models are commonly combined with tracer dispersion models to estimate fluxes using an inverse approach that optimizes emissions to best fit the trace gas mole fraction observations. One way to evaluate the accuracy of atmospheric flux estimation methods is to compare results from independent methods, including approaches in which different meteorological and tracer dispersion models are used. In this work, we use a rich data set of atmospheric methane observations collected during an intensive airborne campaign to compare different methane emissions estimates from the Barnett Shale oil and natural gas production basin in Texas, USA. We estimate emissions based on a variety of different meteorological and dispersion models. Previous estimates of methane emissions from this region relied on a simple model (a mass balance analysis) as well as on ground-based measurements and statistical data analysis (an inventory). We find that in addition to meteorological model choice, the choice of tracer dispersion model also has a significant impact on the predicted downwind methane concentrations given the same emissions field. The dispersion models tested often underpredicted the observed methane enhancements with significant variability (up to a factor of 3) between different models and between different days. We examine possible causes for this result and find that the models differ in their simulation of vertical dispersion, indicating that additional work is needed to evaluate and improve vertical mixing in the tracer dispersion models commonly used in regional trace gas flux inversions.

Shale gas production is a water and energy-intensive process that has expanded rapidly in the United States in recent years. This study compared the life cycle water consumption and greenhouse gas emissions from hydraulic fracturing in the Barnett region of Texas, located in one of the most drought prone regions of the United States. Four wastewater treatment scenarios were compared for produced water management in the Barnett region. For each scenario, the cradle-to-gate life cycle global warming potential and water scarcity footprint was estimated per mega joule of gas produced. The results show a trade-off between water and carbon impacts, because energy is required for treatment of water. A reduction of 49 percent in total water consumed or a 28 percent reduction in the water scarcity footprint in the shale gas production process can be achieved at a cost of a 38 percent increase in global warming potential, if the wastewater management shifted from business as usual to complete desalination and reuse of produced water. The results are discussed in the context of wastewater management options available in Texas.

Unconventional natural gas exploration using hydraulic fracturing has spread rapidly from its “birthplace” in the Barnett Shale to shale plays across the globe, spurring polarized discussions about its environmental and social risks. These debates have engaged many stakeholders, including some individuals with natural and physical science backgrounds. This study presents results from semi-structured, in-depth interviews I conducted with these individuals, which demonstrate how they framed their engagement in these debates. I argue that the process of interacting in politicized debates over hydraulic fracturing impacted how these individuals constructed what it means to provide objective information to the public. In order to demonstrate objectivity, a number of these participants emphasized their role as problem solvers for, rather than opponents of, the oil and gas industry. Also, to provide balance against their critical evaluation of the environmental impacts of hydraulic fracturing, several participants emphasized the (assumed) social benefits of energy exploration. Through exploring the “problems of method” faced by natural and physical scientists engaged in research on controversial energy topics, and their impacts for my own engagement as a qualitative social science researcher, I seek to contribute to our understanding of the challenges scientists face as they engage in energy research.

Clusters of elevated methane concentrations in aquifers overlying the Barnett Shale play have been the focus of recent national attention as they relate to impacts of hydraulic fracturing. The objective of this study was to assess the spatial extent of high dissolved methane previously observed on the western edge of the play (Parker County) and to evaluate its most likely source. A total of 509 well water samples from 12 counties (14,500 km2 ) were analyzed for methane, major ions, and carbon isotopes. Most samples were collected from the regional Trinity Aquifer and show only low levels of dissolved methane (85% of 457 unique locations 20 mg/L) are limited to a few spatial clusters. The Parker County cluster area includes historical vertical oil and gas wells producing from relatively shallow formations and recent horizontal wells producing from the Barnett Shale (depth of ∼1500 m). Lack of correlation with distance to Barnett Shale horizontal wells, with distance to conventional wells, and with well density suggests a natural origin of the dissolved methane. Known commercial very shallow gas accumulations (

David Barnett (Figure ​(Figure11) was born in Lubbock, Texas, on August 17, 1963. Although he lived for short periods in Washington, DC, and Dallas, Texas, he grew up mainly in Lubbock. He graduated from Texas Tech University cum laude with a BA in chemistry in 1985 and from the University of Texas (UT) Southwestern Medical School, ranked number 8 in his class of 197, in 1989. His general surgical internship was at Emory University in Atlanta, Georgia, and his neurosurgical residency from 1990 to 1996 was at the same institution. After completing his residency, Dr. Barnett returned to Dallas, Texas, and joined the staff at Baylor University Medical Center (BUMC); not long thereafter he headed the neurosurgery department. Since he came to BUMC in 1996, the number of neurosurgeons has grown from three to nine, and the number of neurologists and neuroradiologists has also expanded. He has been a major player in the development of the Neuroscience Center at BUMC, and the neurosurgery department has become one of the very best in the country as determined by the U.S. News & World Report annual survey. David is married to Holly Bell Barnett, and they are the proud parents of two offspring. David is a great guy and a tremendous asset to BUMC.

This study develops a multi-level programming model from a life cycle perspective for performing shale-gas supply chain system. A set of leader-follower-interactive objectives with emphases of environmental, economic and energy concerns are incorporated into the synergistic optimization process, named MGU-MEM-MWL model. The upper-level model quantitatively investigates the life-cycle greenhouse gas (GHG) emissions as controlled by the environmental sector. The middle-level one focuses exclusively on system benefits as determined by the energy sector. The lower-level one aims to recycle water to minimize the life-cycle water supply as required by the enterprises. The capabilities and effectiveness of the developed model are illustrated through real-world case studies of the Barnett, Marcellus, Fayetteville, and Haynesville Shales in the US. An improved multi-level interactive solution algorithm based on satisfactory degree is then presented to improve computational efficiency. Results indicate that: (a) the end-use phase (i.e., gas utilization for electricity generation) would not only dominate the life-cycle GHG emissions, but also account for 76.1% of the life-cycle system profits; (b) operations associated with well hydraulic fracturing would be the largest contributor to the life-cycle freshwater consumption when gas use is not considered, and a majority of freshwater withdrawal would be supplied by surface water; (c) nearly 95% of flowback water would be recycled for hydraulic fracturing activities and only about 5% of flowback water would be treated via CWT facilities in the Marcellus, while most of the wastewater generated from the drilling, fracturing and production operations would be treated via underground injection control wells in the other shale plays. Moreover, the performance of the MGU-MEM-MWL model is enhanced by comparing with the three bi-level programs and the multi-objective approach. Results demonstrate that the MGU-MEM-MWL decisions would provide much comprehensive and systematic policies when considering the hierarchical structure within the shale-gas system.

There are two forms of continent ileostomy, Kock pouch and Barnett Continent Intestinal Reservoir. Although ileal pouch-anal anastomosis (IPAA) is the standard procedure for patients with ulcerative colitis or familial adenomatous polyposis who required colectomy, continent ileostomies remain to be valuable options for selected patients. Those patients are not candidates for IPAA mainly due to compromised anal sphincter function or for those who fail pelvic pouches. The nipple valve is a key structure for continent ileostomy, on which the fecal continence is relied. Despite their benefits, surgery for continent ileostomy is a complex procedure with a risk of complications. The most common complications are associated with dysfunctional nipple valve, including valve slippage, stricture, prolapse, and fistula formation. Other complications include pouchitis, Crohn’s disease of the pouch, and pouch bezoars. Fortunately, the risk for neoplasia in continent ileostomy is low. Temporary fecal diversion has been a part of the initial staged pelvic pouch surgery, treatment of refractory pouch disorders, or staged surgical revision or redo of the pouch. Permanent fecal diversion with an ileostomy may be required for patients with pouch failure. All diverted pouches, especially permanent ones, have some degree of endoscopic or histologic inflammation, namely diversion pouchitis. Patients with diversion pouchitis can present with cramping abdominal or pelvic pain and a mucoid or bloody discharge. While diversion pouchitis can be treated with topical anti-inflammatory therapy, surgical reestablishment of bowel continuity is the treatment of choice. Distal pouch stricture is common in a long-term diverted pouch. In addition, diverted pouch may still carry a risk for neoplasia, which requires endoscopic surveillance.

Oil and natural gas operations have continued to expand and move closer to densely populated areas, contributing to growing public concerns regarding exposure to hazardous air pollutants. During the Barnett Shale Coordinated Campaign in October, 2013, ground-based whole air samples collected downwind of oil and gas sites revealed enhancements in several potentially toxic volatile organic compounds (VOCs) when compared to background values. Molar emissions ratios relative to methane were determined for hexane, benzene, toluene, ethylbenzene, and xylene (BTEX compounds). Using methane leak rates measured from the Picarro mobile flux plane (MFP) system and a Barnett Shale regional methane emissions inventory, the rates of emission of these toxic gases were calculated. Benzene emissions ranged between 51 ± 4 and 60 ± 4 kg h-1. Hexane, the most abundantly emitted pollutant, ranged from 642 ± 45 to 1070 ± 340 kg h-1. While observed hydrocarbon enhancements fall below federal workplace standards, results may indicate a link between emissions from oil and natural gas operations and concerns about exposure to hazardous air pollutants. The larger public health risks associated with the production and distribution of natural gas are of particular importance and warrant further investigation, particularly as the use of natural gas increases in the United States and internationally.

With the increasing use of information communication technologies (ICT) for teaching and learning in the early years, this serves as a primary and timely textbook for early childhood education (ECE...

Although oil retention has recently emerged as a key topic of unconventional-shale resource assessment, oil-retention and expulsion controls in organic-rich shales during thermal maturation remain poorly constrained. This study presents an experimental comparison of oil generation, retention, and expulsion in two immature, Type II kerogen-dominated marine shales, the Mississippian Barnett Shale and the Upper Devonian-Lower Mississippian Woodford Shale, mainly with respect to the combined effects of the organic macerals and rock fabric involved. In both cases, miniature core plugs drilled from the given samples were isothermally pyrolyzed at 130 to 425 °C for 72 h under a confining pressure of 68 MPa during gold-tube nonhydrous pyrolysis, corresponding to the thermally immature, early stage of the oil window, the main stage of the oil window, the late stage of the oil window, the main stage of oil cracking to wet gas, and the late stage of oil cracking. Yields of generated oil, retained oil, and expelled oil for the two studied samples were systematically quantified on the basis of mass-balance calculation of measured oil and gas yields, as well as Rock-Eval analyses on pyrolyzed subsamples. Through the six stages of petroleum formation investigated, the principal difference in oil generation was observed in the two studied samples, with approximately 38 to 68% greater yields of generated oil (equivalent to ~130 mg oil/g TOCo) for the Woodford Shale when it evolved into the main and late stages of the oil window. These elevated yields of generated oil for the Woodford Shale were compensated for by additional oil generation resulting from conversion of abundant Type I kerogen-like algae such as Tasmanites and Leiosphaeridia, which lag in onset and have a shorter period of petroleum generation upon maturation. As a response to the difference in oil generation, oil retention was found to be significantly enhanced for the Woodford Shale at equivalent stages, with 0.2 to 1.7 times more free oil (equivalent to 24–105 mg oil/g TOCo) and 0.7 to 3.9 times more sorbed oil (equivalent to 58–76 mg oil/g TOCo) being retained than that of the Barnett Shale, although this effect was not pronounced for oil expulsion. In contrast to the Barnett Shale, relatively low expelled oil yields and expulsion efficiencies both indicate highly limited oil expulsion in the Woodford Shale, implying that the Woodford Shale, whose mineral composition and lithofacies are similar to those of the Barnett Shale, may have a relatively low permeability rock fabric to prevent oil from being expelled. Furthermore, not only significantly higher oil-saturation index (OSI) values but also a wider range of maturity at which the oil crossover effect (OSI > 100 mg/g TOC) occurs is expected for the Woodford Shale when extrapolation to a geological setting occurs. These data suggest that the presence of abundant Type I kerogen-like algae and relatively low permeability rock fabric in the Woodford Shale are critical to significant oil retention during oil generation and expulsion, which jointly raise the possibility of potential commercial shale oil within Type II kerogen-dominated marine shales.

Henry J.M. Barnett, MD, FRCP(C), CC, known by his friends as Barney, was born on February 10, 1922 in Newcastle upon Tyne, England, and died at Toronto, Canada, on Thursday, October 20, 2016. He died peacefully in the company of family and caregivers, after 94 fearless and adventurous years. He was predeceased by his beloved wife Kathleen (Kay) in 2006. A defining moment occurred when, as a boy rambling around the marshes at Ashbridges Bay in Toronto, he chanced upon 2 ornithologists who showed him a hoary redpoll through binoculars. From then on, birds, natural science, and eventually medical science captivated him. In 1944, he graduated from University of Toronto Medical School, where he met a beautiful nurse, Kathleen (Kay), whom he married. He continued his studies in Toronto, then Queen Square, London, United Kingdom, and Oxford, specializing in Neurology, which he practiced and taught for over 45 years in Toronto and then London, Ontario. His clinical research led him to contribute to scientific knowledge on stroke prevention, early detection, clinical care, and treatment for which he received acclaim and prizes worldwide, including an Honorary Doctorate of Letters from Oxford, the Karolinska Stroke Award for Excellence in Stroke Research in Stockholm, and the Companion of the Order of Canada. In later life, he pursued his passion for the natural world as a volunteer advocate with the Nature Conservancy of Canada for the Happy Valley Forest in King Township, Ontario. He bought property there when his children were young and used the 80 acres of forest, ponds, and meadows to pass on his and Kay’s delight in Nature to the Nature Conservancy of Canada. Barney was the Principal Investigator of the first randomized trial to show that Aspirin reduced the risk of stroke,1 the NASCET (North American Carotid Endarterectomy Trial), …

We present estimates of regional methane (CH4) emissions from oil and natural gas operations in the Barnett Shale, Texas, using airborne atmospheric measurements. Using a mass balance approach on eight different flight days in March and October 2013, the total CH4 emissions for the region are estimated to be 76 ± 13 × 10(3) kg hr(-1) (equivalent to 0.66 ± 0.11 Tg CH4 yr(-1); 95% confidence interval (CI)). We estimate that 60 ± 11 × 10(3) kg CH4 hr(-1) (95% CI) are emitted by natural gas and oil operations, including production, processing, and distribution in the urban areas of Dallas and Fort Worth. This estimate agrees with the U.S. Environmental Protection Agency (EPA) estimate for nationwide CH4 emissions from the natural gas sector when scaled by natural gas production, but it is higher than emissions reported by the EDGAR inventory or by industry to EPA's Greenhouse Gas Reporting Program. This study is the first to show consistency between mass balance results on so many different days and in two different seasons, enabling better quantification of the related uncertainty. The Barnett is one of the largest production basins in the United States, with 8% of total U.S. natural gas production, and thus, our results represent a crucial step toward determining the greenhouse gas footprint of U.S. onshore natural gas production.

We present high time resolution airborne ethane (C2H6) and methane (CH4) measurements made in March and October 2013 as part of the Barnett Coordinated Campaign over the Barnett Shale formation in Texas. Ethane fluxes are quantified using a downwind flight strategy, a first demonstration of this approach for C2H6. Additionally, ethane-to-methane emissions ratios (C2H6:CH4) of point sources were observationally determined from simultaneous airborne C2H6 and CH4 measurements during a survey flight over the source region. Distinct C2H6:CH4 × 100% molar ratios of 0.0%, 1.8%, and 9.6%, indicative of microbial, low-C2H6 fossil, and high-C2H6 fossil sources, respectively, emerged in observations over the emissions source region of the Barnett Shale. Ethane-to-methane correlations were used in conjunction with C2H6 and CH4 fluxes to quantify the fraction of CH4 emissions derived from fossil and microbial sources. On the basis of two analyses, we find 71-85% of the observed methane emissions quantified in the Barnett Shale are derived from fossil sources. The average ethane flux observed from the studied region of the Barnett Shale was 6.6 ± 0.2 × 10(3) kg hr(-1) and consistent across six days in spring and fall of 2013.

Atmospheric methane (CH4) was measured using a mobile laboratory to quantify fugitive CH4 emissions from Oil and Natural Gas (ONG) operations in the Barnett Shale area. During this Barnett Coordinated Campaign we sampled more than 152 facilities, including well pads, compressor stations, gas processing plants, and landfills. Emission rates from several ONG facilities and landfills were estimated using an Inverse Gaussian Dispersion Model and the Environmental Protection Agency (EPA) Model AERMOD. Model results show that well pads emissions rates had a fat-tailed distribution, with the emissions linearly correlated with gas production. Using this correlation, we estimated a total well pad emission rate of 1.5 × 10(5) kg/h in the Barnett Shale area. It was found that CH4 emissions from compressor stations and gas processing plants were substantially higher, with some "super emitters" having emission rates up to 3447 kg/h, more then 36,000-fold higher than reported by the Environmental Protection Agency (EPA) Greenhouse Gas Reporting Program (GHGRP). Landfills are also a significant source of CH4 in the Barnett Shale area, and they should be accounted for in the regional budget of CH4.

This study estimates reservoir quality and free-gas storage capacity of the Barnett Shale in the main natural-gas producing area of the Fort Worth basin by mapping log-derived thickness, porosity, and porosity-feet. In the Barnett Shale, the density porosity (DPHI) log curve is a very useful tool to quantitatively assess shale gas resources, and gamma-ray (GR) and neutron porosity log curves are important factors in identifying the shale gas reservoir. The key data were digital logs from 146 wells selected based on the availability of GR and density log curves, log quality, and good spatial distribution. The Barnett Shale pay zone was determined on the basis of (1) DPHI >5%, (2) high GR values (commonly >∼90 API units), (3) no significant intercalated carbonate-rich beds, and (4) individual pay zones being thick enough to be commercially successful for the current design of horizontal wells. In the study area, the Barnett Shale pay zone varies from about 165 ft (50 m) to 420 ft (128 m) in thickness (H). Average DPHI values of individual wells for the pay zone vary from 8.5 to 14.0%. Porosity-feet maps of the pay zone show that areas of high DPHI-H values coincide with areas of high natural gas production, indicating that log-derived porosity-feet maps are a good method for evaluating reservoir quality and assessing natural gas resource in the Barnett Shale play. A limitation to this method is shown in the northwestern corner of the study area, which is located in the liquids-rich window with lower thermal maturity.

Methane (CH4) is an important greenhouse gas with its mixing ratio increasing in the global atmosphere. Identifying fingerprints of CH4 emissions is critical to understanding potential impacts of various anthropogenic sources in the Greater Houston area (GHA) and extensive natural gas operations in the Barnett Shale area (BSA) of Texas. Stable carbon isotope ratios of CH4 (δ13CCH4) has been proposed to be a useful technique for differentiating individual CH4 sources. Measurements of CH4 mixing ratios and δ13CCH4 were sampled using a mobile laboratory equipped with cavity ring-down spectrometers (CRDS). Areal CH4 distributions and the background δ13CCH4 signature were obtained from filtered ambient signals; −47.0‰ (GHA) and − 48.5‰ (BSA) were calculated. The fingerprint of thirty-three anthropogenic sources in the two study areas were sampled with forty-four δ13C analyses conducted. Repeated measurements indicated the natural variation of δ13CCH4 signatures of individual CH4 sources. An unexpected massive CH4 fugitive leak was detected near the San Jacinto River Fleet site in Houston exhibiting an δ13CCH4 value around −42‰. Our results and findings demonstrate the utility of δ13CCH4for facilitating emission inventories and atmospheric modeling.

This paper presents a methodology for quantifying uncertainty in production forecasts using Logistic Growth Analysis (LGA) and time series modeling. The applicability of the proposed method is tested by history matching production data and providing uncertainty bounds for forecasts from eight Barnett Shale counties. In the methodology presented, the trend in the production data was determined using two different non-linear regression schemes. Predicted trends were subtracted from the actual production data to generate two sets of stationary residual time series. Time series analysis techniques (Auto Regressive Moving Average models) were thereafter used to model and forecast residuals. These residual forecasts were incorporated with trend forecasts to generate our final 80% CI. To check reliability of the proposed method, we tested it on 100 gas wells with at least 100 months of available production history. The CIs generated covered true production 84% and 92% of the time when 40 and 60 months of production data were used for history matching respectively. An auto-regressive model of lag 1 was found to best fit residual time series in each case. The proposed methodology is an efficient way to generate production forecasts and to reliably estimate the uncertainty. The method is computationally inexpensive and easy to implement. The utility of the procedure presented is not limited to gas wells and can be applied to any type of well or group of related wells.

This paper presents research findings on life cycle greenhouse gas (GHG) emissions associated with natural gas production in the Barnett Shale play in Texas. The data sources and approach used in this study differ significantly from previous efforts. The authors used inventories from the year 2009 tracking emissions of regulated air pollutants by the natural gas industry in the Barnett Shale play. These inventories were collected and screened by the Texas Commission on Environmental Quality (TCEQ). These data cover the characteristics and volatile organic compound (VOC) emissions of more than 16,000 individual sources in shale gas production and processing. Translating estimated emissions of VOCs into estimates of methane and carbon dioxide emissions was accomplished through the novel compilation of spatially heterogeneous gas composition analyses. Life cycle greenhouse gas emissions associated with electricity generated from Barnett Shale gas extracted in 2009 were found to be very similar to conventional natural gas and less than half those of coal-fired electricity generation.

The color field paintings of Barnett Newman, one of the great American abstract expressionist painters, are seminal works of the modern era. They feature large flat fields of vibrant colors intended to allow the viewer to connect with the paintings in immediate, visceral ways. Despite the apparent simplicity of his compositions, Newman considered himself an intuitive painter and allowed his compositions to evolve during the painting process. Two paintings in the Menil Collection, Untitled 2 (1950) and Unfinished Painting [Blue and Brown 1970—#2] (1970) display visual evidence of former states, but attempts to elucidate earlier compositions by X-radiography were inconclusive due to the lack of contrast in paint densities. We applied limited sampling and used a handheld X-ray fluorescence spectrometer in a ‘scanning’ manner to determine the color and composition of the previous states of these paintings to help us better understand their evolution. Newman altered his initial cadmium red and alizarin composition in Untitled 2 (1950) by overpainting the alizarin region with a wider band of Mars black paint. He then modulated the surface of the black by partially covering it with a carbonaceous black with a different gloss. For Unfinished Painting [Blue and Brown 1970—#2] (1970), Newman not only changed the cadmium red to an umber but simplified the composition, removing multiple zips and refining it to its current monumental state. This evidence of Newman’s decision-making processes permits a tantalizing glimpse of the artist consistently looking both ahead and backward, experimenting and revisiting.

The main goal of this paper was to predict the total organic carbon (TOC) from well logs data using the multilayer perceptron (MLP) neural network machine. This can replace the Schmoker’s method in case of discontinuous measurement of the bulk density log. The MLP machine is composed of three layers, an input layer with four neurons corresponding to the Gamma ray, the neutrons porosity, and the slowness of the P and S waves well logs. The output layer is formed with one neuron, which corresponds to the predicted TOC log, and a hidden layer with ten neurons. The MLP machine is trained using the Levenberg–Marquardt algorithm. Data of two horizontal wells drilled in the lower Barnett formation located in USA are used. Comparison between the predicted and calculated TOC log using the Schmoker’s method clearly shows the use of the neural network method to predict the TOC in shale gas reservoirs.

Microwave is a kind of wireless communication using radio link transmission at high frequency medium between two base stations in cellular systems. Microwave link should be line of sight (LOS) between transmitter and receiver (no obstacle). But, in the real case, there are some obstacles in microwave link between two base stations. Therefore, this paper uses a microwave passive repeater to solve the obstacle problems. The passive repeater is used to repeat information signals by changing the direction of the radio link transmission. This paper implements Barnett Vigants and ITU-R P.530–7/8 methods in passive repeater using software simulation. The difference between two methods is the availability value due to multipath and unavailability value due to rain. On a microwave transmission network using the Barnett Vigants method, resulting higher unavailability value than the use of ITU-R method P.530 7/8. The unavailability value using Barnett Vigants method obtained was 0.023%, it means the outage time of link microwave is 7244 second per year. If compared with metode ITU-R P.530 7/8 method, the unavailability was 0.000087 % or outage time system is for 26 second per year. So the availability using ITU-R P.530 7/8 method is 99. 9999133%.

The three generalized Barnett–Lothe tensors L, S and H are frequently encountered in the extended Stroh formalism of two-dimensional deformation of anisotropic magneto-electro-elastic materials. Meantime, they are directly related to the admittance matrix Y, which is required to characterize the crack-tip field. In this paper, the elements of L, S and H together with Y are constructed using a modified Lekhinitskii formalism for general anisotropic magneto-electro-elastic materials. As a typical case, the three generalized Barnett–Lothe tensors are explicitly expressed in terms of the reduced generalized elastic compliances for transversely isotropic magneto-electro-elastic materials. A simple example is presented to validate these expressions.

Production of natural gas from shale formations is bringing drilling and production operations to regions of the United States that have seen little or no similar activity in the past, which has generated considerable interest in potential environmental impacts. This study focused on the Barnett Shale Fort Worth Basin in Texas, which saw the number of gas-producing wells grow from 726 in 2001 to 15,870 in 2011. This study aimed to measure fence line concentrations of methane and hydrogen sulfide at natural gas production sites (wells, liquid storage tanks, and associated equipment) in the four core counties of the Barnett Shale (Denton, Johnson, Tarrant, and Wise). A mobile measurement survey was conducted in the vicinity of 4788 wells near 401 lease sites, representing 35% of gas production volume, 31% of wells, and 38% of condensate production volume in the four-county core area. Methane and hydrogen sulfide concentrations were measured using a Picarro G2204 cavity ring-down spectrometer (CRDS). Since the research team did not have access to lease site interiors, measurements were made by driving on roads on the exterior of the lease sites. Over 150 hr of data were collected from March to July 2012. During two sets of drive-by measurements, it was found that 66 sites (16.5%) had methane concentrations >3 parts per million (ppm) just beyond the fence line. Thirty-two lease sites (8.0%) had hydrogen sulfide concentrations >4.7 parts per billion (ppb) (odor recognition threshold) just beyond the fence line. Measured concentrations generally did not correlate well with site characteristics (natural gas production volume, number of wells, or condensate production). t tests showed that for two counties, methane concentrations for dry sites were higher than those for wet sites. Follow-up study is recommended to provide more information at sites identified with high levels of methane and hydrogen sulfide. Implications:Information regarding air emissions from shale gas production is important given the recent increase in number of wells in various regions in the United States. Methane, the primary natural gas constituent, is a greenhouse gas; hydrogen sulfide, which can be present in gas condensate, is an odor-causing compound. This study surveyed wells representing one-third of the natural gas production volume in the Texas Barnett Shale and identified the percent of sites that warrant further study due to their fence line methane and hydrogen sulfide concentrations.

Background:\ud \ud There are currently no studies on visual impairment and sarcopenia. We investigated the cross-sectional association between objectively measured far vision impairment and sarcopenia in a nationally representative sample of older adults aged 65 years and over from six low- and middle-income countries (LMICs).\ud \ud Methods:\ud \ud Cross-sectional, community-based data from the study on global ageing and adult health (SAGE) were analyzed. Far vision acuity was measured using the tumbling E LogMAR chart and classified as: no vision impairment (6/12 or better); mild vision impairment (6/18 or better but worse than 6/12); moderate vision impairment (6/60 or better but worse than 6/18); severe vision impairment (worse than 6/60). Sarcopenia was defined as having low skeletal muscle mass and either a slow gait speed or a weak handgrip strength. Associations were assessed with multivariable logistic regression.\ud \ud Results:\ud \ud Fourteen thousand five hundred and eighty five individuals aged ≥ 65 years were included in the analysis [mean (SD) age 72.6 (11.5) years; 54.1% females]. After adjustment for multiple potential confounders, compared to those with no vision impairment, the OR (95% CI) for sarcopenia in those with mild, moderate, and severe vision impairment were 1.10 (0.87–1.40), 1.69 (1.25–2.27), and 3.38 (1.69–6.77), respectively. The estimates for females and males were similar.\ud \ud Conclusions:\ud \ud The odds for sarcopenia increased with increasing severity of far vision impairment among older people in LMICs. The mere co-occurrence of these conditions is concerning, and it may be prudent to implement interventions to address/prevent sarcopenia in those with far vision impairment through the promotion of physical activity and appropriate nutrition.

Aim: The association between visual impairment and mild cognitive impairment (MCI) has not been investigated to date. Thus, we assessed this association among older adults from six low- and middle-income countries (LMICs) (China, India, Ghana, Mexico, Russia, and South Africa) using nationally representative datasets. Methods: Cross-sectional, community-based data from the WHO Study on global AGEing and adult health (SAGE) were analyzed. Visual acuity was measured using the tumbling ElogMAR chart, and vision impairment (at distance and near) was defined as visual acuity worse than 6/18 (0.48 logMAR) in the better-seeing eye. The definition of MCI was based on the National Institute on Aging-Alzheimer’s Association criteria. Multivariable logistic regression was conducted. Results: Data on 32,715 individuals aged ≥ 50years [mean (SD) age 62.1 (15.6) years; 51.2% females] were analyzed. Compared to those without far or near vision impairment, those with near vision impairment but not far vision impairment (OR = 1.33; 95% CI = 1.16–1.52), and those with both far and near vision impairment (OR = 1.70; 95% CI = 1.27–2.29) had significantly higher odds for MCI. Only having far vision impairment was not significantly associated with MCI. Conclusions: Visual impairment is associated with increased odds for MCI among older adults in LMICs with the exception of far vision impairment only. Future longitudinal and intervention studies should examine causality and whether improvements in visual acuity, or early intervention, can reduce risk for MCI and ultimately, dementia. © 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG part of Springer Nature.

A novel slow wave vacuum electron device circuit, the so-called ldquoBarnett-Shin traveling wave tube (TWT) circuitrdquo, which consists of a half-period-staggered double vane array and a high aspect ratio sheet beam, has been conceived for high power millimeter and submillimeter wave amplification/ oscillation applications requiring extremely wide bandwidth as well as compact size and light weight. Particle-in-cell simulations based on a finite-difference-time-domain algorithm have shown that this circuit has a very wide intrinsic bandwidth (in excess of 50 GHz around the operating frequency of 220 GHz) with a moderate gain of 13 dB. Also, the saturated electronic conversion efficiency is 3 ~ 5.5%, which corresponds to radiation power of 150 ~ 275 W, assuming a beam power of 5 kW. Of particular importance, this structure is based on TE-fundamental mode interaction, which can avoid complex overmoding instability usually causing spurious signal oscillations in the conventional high aspect ratio structure. Moreover, this planar circuit has a simple two-dimensional geometry so as to be thermally and mechanically robust as well as compatible with conventional micro-fabrication techniques. This concept will open promising opportunities in potential applications of versatile electronic devices to the millimeter and submillimeter wave region.

We evaluate the economics of drilling new wells in the Barnett Shale, Fort Worth Basin, Texas. The analysis is the most granular public study to date because it is based on 10 productivity tiers and it treats low and high Btu (British thermal unit) segments of the play differently. The study is unique in its use of transient linear drainage production profiles that match the physics of the system and fit the production history in the Barnett very well. Average low Btu wells in the top two tiers are viable at $4/MMBtu, whereas average high Btu wells in the same tiers are economic at $2/MMBtu. Dry gas wells are the most sensitive to fluctuations in the price of natural gas whereas high Btu wells are also sensitive to the prices of oil and natural gas liquids. There is a distribution of productivity within each tier, with better wells requiring a much lower price to be viable than the average well. The granular subdivision of productivity, low versus high Btu, and intra-tier quality variation help to explain historical drilling patterns and also allow us to predict future development patterns in the field accurately as demonstrated for 2011 and 2012 in Browning et al. [4] .

Background-\ud \ud There are no multi-country studies on the association between informal caregiving and anxiety from low- and middle-income countries (LMICs). Therefore, we investigated this relationship in a large predominantly nationally representative sample from 47 LMICs.\ud \ud Methods-\ud \ud Cross sectional data from the World Health Survey were analyzed. Anxiety symptoms referred to severe or extreme problems with worries or anxiety in the past 30 days.\ud \ud Information on caregiving in the past 12 months was obtained. Multivariable logistic regression analysis adjusting for age, sex, marital status, education, household size, employment, disability, and country was conducted. Data on 237,952 individuals aged ≥18 years [mean (SD) age 38.4 (16.0) years; 50.8% female] were analyzed.\ud \ud Results-\ud \ud After adjustment for potential confounders, caregiving was positively associated with anxiety symptoms (OR = 1.52; 95%CI = 1.40, 1.65). Greater number of caregiving activities was associated with higher odds for anxiety symptoms dose-dependently, with the OR (95%CI) for engagement in 5 activities (vs. no caregiving) being 2.19 (1.86–2.58).\ud \ud Conclusion-\ud \ud Caregiving is associated with higher odds for anxiety symptoms among adults in LMICs. Given the increasing importance of informal caregivers in long-term care provision and the fact that good health of caregivers is vital to sustain this system, interventions to address mental health of caregivers in LMICs are urgently needed.

June 2012 The Journal of American History 229 Just as the discovery of oil at Spindletop near the Texas coast in 1901 launched a new chapter in the development of the American petroleum industry, a century later the opening of massive natural gas production in north Texas from a geological formation called the Barnett Shale has begun a new era in world energy. Drilling in the Barnett Shale since 2000 touched off an urban gas boom throughout the greater Fort Worth metropolitan area. Far more significant, however, the Barnett Shale bonanza has revealed the incredible petroleum potential in shale formations throughout the United States. “Shale booms” have materialized in places as far flung as south Texas, North Dakota, and Pennsylvania, as well as overseas. Shale production could offer the United States far greater energy independence than anyone could have anticipated a decade ago, but the technology essential to it has also generated environmental apprehensions and controversy. As is so often true in the history of American petroleum exploration, the pioneer wildcatter to open the Barnett Shale was an independent prospector, the Houstonian George Mitchell, who spent seventeen years and millions of dollars to obtain natural gas from the formation. His story demonstrates how independent oilmen do business and why they remain important in an industry best known for its giant players. Mention the petroleum industry and most Americans are likely to think of Big Oil— the major multinational companies such as ExxonMobil—but the American oil industry has always included a majority of small participants that are not vertically integrated and are usually regionally focused. In the nineteenth century, the term independent in the oil industry referred to any firm or operator that existed outside John D. Rockefeller’s Standard Oil empire; by the 1920s it had come to stand for the smaller members of the oil and gas industry. Most domestic wildcat exploration—the search for oil and gas in areas far from existing production or in rock formations considered unlikely for commercial success—has been done by independents, perhaps because they usually do not have to justify unconventional projects to conservative boards of directors. Independent individual prospectors such as Patillo Higgins at Spindletop and Columbus Marion “Dad” Joiner in east Texas were free to challenge industry orthodoxy and brought in spectacular discoveries. Most independents, however, are not in the game to obtain giant finds. With The Seventeen-Year Overnight Wonder: George Mitchell and Unlocking the Barnett Shale

Ethane, propane, and carbon dioxide show reversed carbon isotopic maturity trends in natural gas produced from the Barnett and Fayetteville Shales at thermal maturities greater than ∼1.5% VRE. At this high level of thermal maturity, the iso-butane to n-butane ratio also reverses, suggesting wet gas cracking has occurred, generating more gas molecules in the same volume resulting in overpressure, and increased stabilized production rates in the Barnett. Hydrothermal fluids from the nearby Ouachita Thrust front apparently enhanced the maturity of the Fayetteville and Barnett shales. Water-hydrocarbon reactions at these high maturities may account for the isotopic reversals.

In quantum mechanics the position and momentum operators are related to each other via the Fourier transform. In the same way, here we show that the so-called Pegg–Barnett phase operator can be obtained by the application of the discrete Fourier transform to the number operators defined in a finite-dimensional Hilbert space. Furthermore, we show that the structure of the London–Susskind–Glogower phase operator, whose natural logarithm gives rise to the Pegg–Barnett phase operator, is contained in the Hamiltonian of circular waveguide arrays. Our results may find applications in the development of new finite-dimensional photonic systems with interesting phase-dependent properties.

Summary A Barnett shale water-production data set from approximately 11,000 completions was analyzed using conventional statistical techniques. Additionally, a water/hydrocarbon ratio and first-derivative diagnostic-plot technique developed elsewhere for conventional reservoirs was extended to analyze Barnett shale water-production mechanisms. To determine hidden structure in well and production data, self-organizing maps and the k-means algorithm were used to identify clusters in data. A competitive-learning-based network was used to predict the potential for continuous water production from a new well, and a feed-forward neural network was used to predict average water production for wells drilled in Denton and Parker Counties, Texas, of the Barnett shale. Using conventional techniques, we concluded that for wells of the same completion type, location is more important than time of completion or hydraulic-fracturing strategy. Liquid loading has potential to affect vertical more than horizontal wells. Different features were observed in the spreadsheet diagnostic plots for wells in the Barnett shale, and we made a subjective interpretation of these features. We find that 15% of the horizontal and vertical wells drilled in Denton County have a load-water-recovery factor greater than unity. Also, 15 and 35% of the horizontal and vertical wells drilled, respectively, in Parker County have a load-recovery factor greater than unity.The use of both self-organizing maps and the k-means algorithm showed that the data set is divided into two main clusters. The physical properties of these clusters are unknown but interpreted to represent wells with high water throughput and those with low water throughput. Expected misclassification error for the competitive-learning-based tool was approximately 10% for a data set containing both vertical and horizontal wells. The average prediction error for the neural-network tool varied between 10 and 26%, depending on well type and location.Results from this work can be used to mitigate risk of water problems in new Barnett shale wells and predict water issues in other shale plays. Engineers are provided a tool to predict potential for water production in new wells. The method used to develop this tool can be used to solve similar challenges in new and existing shale plays.

This paper presents a probabilistic decline curve workflow to model shale gas production from the Barnett, Fayetteville, Haynesville, and Woodford shales. Ranges of model input parameters for four gas shales are provided to guide the preparation of uniform and triangle probability distributions. The input parameter ranges represent realistic distributions of model parameters for specific gas shales.

Information regarding air emissions from shale gas extraction and production is critically important given production is occurring in highly urbanized areas across the United States. Objectives of this exploratory study were to collect ambient air samples in residential areas within 61 m (200 feet) of shale gas extraction/production and determine whether a "fingerprint" of chemicals can be associated with shale gas activity. Statistical analyses correlating fingerprint chemicals with methane, equipment, and processes of extraction/production were performed. Ambient air sampling in residential areas of shale gas extraction and production was conducted at six counties in the Dallas/Fort Worth (DFW) Metroplex from 2008 to 2010. The 39 locations tested were identified by clients that requested monitoring. Seven sites were sampled on 2 days (typically months later in another season), and two sites were sampled on 3 days, resulting in 50 sets of monitoring data. Twenty-four-hour passive samples were collected using summa canisters. Gas chromatography/mass spectrometer analysis was used to identify organic compounds present. Methane was present in concentrations above laboratory detection limits in 49 out of 50 sampling data sets. Most of the areas investigated had atmospheric methane concentrations considerably higher than reported urban background concentrations (1.8-2.0 ppm(v)). Other chemical constituents were found to be correlated with presence of methane. A principal components analysis (PCA) identified multivariate patterns of concentrations that potentially constitute signatures of emissions from different phases of operation at natural gas sites. The first factor identified through the PCA proved most informative. Extreme negative values were strongly and statistically associated with the presence of compressors at sample sites. The seven chemicals strongly associated with this factor (o-xylene, ethylbenzene, 1,2,4-trimethylbenzene, m- and p-xylene, 1,3,5-trimethylbenzene, toluene, and benzene) thus constitute a potential fingerprint of emissions associated with compression.Information regarding air emissions from shale gas development and production is critically important given production is now occurring in highly urbanized areas across the United States. Methane, the primary shale gas constituent, contributes substantially to climate change; other natural gas constituents are known to have adverse health effects. This study goes beyond previous Barnett Shale field studies by encompassing a wider variety of production equipment (wells, tanks, compressors, and separators) and a wider geographical region. The principal components analysis, unique to this study, provides valuable information regarding the ability to anticipate associated shale gas chemical constituents.

Shale is an increasingly important source of natural gas in the United States. The gas is held in fine pores that need to be accessed by horizontal drilling and hydrofracturing techniques. Understanding the nature of the pores may provide clues to making gas extraction more efficient. We have investigated two Mississippian Barnett Shale samples, combining small-angle neutron scattering (SANS) and ultrasmall-angle neutron scattering (USANS) to determine the pore size distribution of the shale over the size range 10 nm to 10 μm. By adding deuterated methane (CD4) and, separately, deuterated water (D2O) to the shale, we have identified the fraction of pores that are accessible to these compounds over this size range. The total pore size distribution is essentially identical for the two samples. At pore sizes >250 nm, >85% of the pores in both samples are accessible to both CD4 and D2O. However, differences in accessibility to CD4 are observed in the smaller pore sizes (∼25 nm). In one sample, CD4 penetrated ...

Summary When performing multiple fracture treatments in horizontal Barnett shale wells, many operators choose to use artificial lift to remove fracture fluids rather than incur the expense of energized fluids that may not be effective. Gas lift has been a popular artificial lift method to remove fracture fluids because it allows for high liquid flow rates and is excellent at handling flowback sand. Its disadvantage is that a source of lift gas is required to initiate gas lift, with this source typically being other nearby gas wells or a third-party gas pipeline. In new exploration areas such as the Barnett, often neither is available. Operators resort to costly nitrogen-membrane units to provide lift gas but are left with questions about the net gas produced (since returning nitrogen and produced natural gas are combined downhole then vented to the atmosphere). A new system (patent pending) has been developed that addresses gas lift's issues of initially filling the system with lift gas, as well as maintaining this gas so that additional gas is not required. Being a closed-loop system, it also provides for very accurate measurement of net-gas production by measuring any gas in excess of that needed for lift, and discharging the same to a flare stack. The paper will describe the major components used in this system, present a case history, and address the significant cost reductions and other benefits realized.