Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures

Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo

Effects of Streambed Conductance on Stream Depletion

Stream depletion, which is the reduction in flow rate of a stream or river due to the extraction of groundwater in a hydraulically connected stream-aquifer system, is often estimated using numerical models. The accuracy of these models depends on the appropriate parameterization of aquifer and streambed hydraulic properties. Streambed conductance is a parameter that relates the head difference between the stream and aquifer to flow across the stream channel. It is a function of streambed hydraulic conductivity and streambed geometry. In natural systems, streambed conductance varies spatially throughout the streambed; however, stream depletion modeling studies often ignore this variability. In this work, we use numerical simulations to demonstrate that stream depletion estimates are sensitive to a range of streambed conductance values depending on aquifer properties. We compare the stream depletion estimates from various spatial patterns of streambed conductance to show that modeling streambed conductance as a homogeneous property can lead to errors in stream depletion estimates. We use the results to identify feasible locations for proposed pumping wells such that the stream depletion due to pumping from a well within this feasible region would not exceed a prescribed threshold value, and we show that incorrect assumptions of the magnitude and spatial variability of streambed conductance can affect the size and shape of the feasible region

Effects of Streambed Conductance on Stream Depletion

Stream depletion, which is the reduction in flow rate of a stream or river due to the extraction of groundwater in a hydraulically connected stream-aquifer system, is often estimated using numerical models. The accuracy of these models depends on the appropriate parameterization of aquifer and streambed hydraulic properties. Streambed conductance is a parameter that relates the head difference between the stream and aquifer to flow across the stream channel. It is a function of streambed hydraulic conductivity and streambed geometry. In natural systems, streambed conductance varies spatially throughout the streambed; however, stream depletion modeling studies often ignore this variability. In this work, we use numerical simulations to demonstrate that stream depletion estimates are sensitive to a range of streambed conductance values depending on aquifer properties. We compare the stream depletion estimates from various spatial patterns of streambed conductance to show that modeling streambed conductance as a homogeneous property can lead to errors in stream depletion estimates. We use the results to identify feasible locations for proposed pumping wells such that the stream depletion due to pumping from a well within this feasible region would not exceed a prescribed threshold value, and we show that incorrect assumptions of the magnitude and spatial variability of streambed conductance can affect the size and shape of the feasible region

The 1991 Census of Least Terns and Piping Plovers in Nebraska

We counted least terns (Sterna antillarum) and piping plovers (Charadrius melodus) in Nebraska during June and July, 1991. This undertaking was part of an international effort to census the threatened piping plover throughout Canada and the United States. The U.S. Fish and Wildlife Service (USFWS) (1988) has called for the censusing of piping plovers every five years to monitor the status of the species and to gage the effectiveness of recovery efforts. This first international census of the piping plover has been organized by the USFWS\u27s Great Lakes/Northern Great Plains Piping Plover recovery team. The census is one of the first attempts to complete a total count of one species of breeding shorebird. The least tern in the Great Plains is endangered and also requires periodic censusing (USFWS 1990). Because both species nest on the same river sandbars and adjacent sand and gravel pits (sandpits) in Nebraska, least terns were counted during the census of piping plovers. Study Area and Methods The distribution of the least tern and piping plover in Nebraska has been well known for several years. The Nebraska Game and Parks Commission, Platte River Whooping Crane Habitat Maintenance Trust, USFWS, and others began censusing in the late 1970s. In the intervening years most stretches of river and sandpits used for nesting were identified. Sandpits (Figure 1) are areas mined for the commercial sale of sand and gravel and are usually located within 2-3 miles of a river. Three areas we included as sandpits consisted of sand and gravel that had been side casted along diversion canals from the Loup River (Loup River Diversion), South Platte River (Korty Diversion), and from near the confluence of the North and South Platte rivers (Central Diversion). Periodic dredging to keep the canals open creates and maintains a large expanse of barren sand and gravel. The barren sand and gravel at pits is similar to the barren sandbar substrate found in rivers (Kirsch 1991, Lingle 1990, Wilson 1991). We also surveyed pits that were no longer being actively mined but contained some suitable nesting substrate. Vegetation eventually will cover inactive sand and gravel areas and render them unsuitable as nesting habitat

A Review of Well Integrity Based on Field Experience at Carbon Utilization and Storage Sites

Maintaining well integrity is critical to the success of geologic carbon storage (GCS) and carbon dioxide enhanced oil recovery (CO2-EOR) operations. Wells that experience leakage because of integrity issues can potentially become a risk to the environment or human health if they release previously captured CO2 back into the atmosphere or into freshwater aquifers. There are many GCS and CO2-EOR sites in operation around the world. However, well integrity experiences at these sites are not widely documented in the public domain. This study details findings from a survey of well integrity experiences elicited from operators of GCS and CO2-EOR sites. The goal of the survey was to obtain information about site characteristics and operator experiences with well integrity, monitoring methods, and risk assessment of legacy wells. Literature relevant to the survey questions was also reviewed and summarized to provide context for survey responses and identify areas where field experiences with well integrity do and do not align with the current state of research. We highlight the current state-of-practice, identify research needs, and provide context for future interactions between researchers, operators, and regulators on issues related to well integrity

A Review of Well Integrity Based on Field Experience at Carbon Utilization and Storage Sites

Maintaining well integrity is critical to the success of geologic carbon storage (GCS) and carbon dioxide enhanced oil recovery (CO2-EOR) operations. Wells that experience leakage because of integrity issues can potentially become a risk to the environment or human health if they release previously captured CO2 back into the atmosphere or into freshwater aquifers. There are many GCS and CO2-EOR sites in operation around the world. However, well integrity experiences at these sites are not widely documented in the public domain. This study details findings from a survey of well integrity experiences elicited from operators of GCS and CO2-EOR sites. The goal of the survey was to obtain information about site characteristics and operator experiences with well integrity, monitoring methods, and risk assessment of legacy wells. Literature relevant to the survey questions was also reviewed and summarized to provide context for survey responses and identify areas where field experiences with well integrity do and do not align with the current state of research. We highlight the current state-of-practice, identify research needs, and provide context for future interactions between researchers, operators, and regulators on issues related to well integrity.publishedVersio

Environmental risks and opportunities of orphaned oil and gas wells in the United States

Abstract: Hundreds of thousands of documented and undocumented orphaned oil and gas wells exist in the United States (U.S.). These wells have the potential to contaminate water supplies, degrade ecosystems, and emit methane and other air pollutants. Thus, orphaned wells present risks to climate stability and to environmental and human health, which can be reduced by plugging. To quantify environmental risks and opportunities of well plugging at the national level, we analyze data on 81 857 documented orphaned wells across the U.S. We find that > 4.6 million people live within 1 km of a documented orphaned well. 35% of the documented orphaned wells are located within 1 km of a domestic groundwater well, yet only 8% of the wells have groundwater quality data within a 1 km radius. Methane emissions from the documented orphaned wells represent approximately 3%–6% of total U.S. methane emissions from abandoned oil and gas wells, but this estimate is based on measurements at < 0.03% of U.S. abandoned wells. 91% of the documented orphaned wells overlie formations favorable for geologic storage of carbon dioxide and hydrogen, meaning that orphaned well plugging can reduce leakage risks from future storage projects. Finally, we estimate plugging costs for documented orphaned wells to exceed the $4.7 billion federal funding by 30%–80%, emphasizing the importance of prioritizing federal spending on wells with large remediation benefits. Overall, environmental monitoring data are not extensive enough to quantify risks, especially those related to air and water quality and human health. Plugging orphaned wells can provide opportunities for geologic storage of carbon dioxide and hydrogen and geothermal energy development, thereby facilitating efforts to transition to net-zero energy systems. Our analysis on environmental risks and opportunities of orphaned wells provides a framework that can be used to manage the millions of documented and undocumented orphaned wells in the U.S. and abroad

Environmental risks and opportunities of orphaned oil and gas wells in the United States

Hundreds of thousands of documented and undocumented orphaned oil and gas wells exist in the United States (U.S.). These wells have the potential to contaminate water supplies, degrade ecosystems, and emit methane and other air pollutants. Thus, orphaned wells present risks to climate stability and to environmental and human health, which can be reduced by plugging. To quantify environmental risks and opportunities of well plugging at the national level, we analyze data on 81 857 documented orphaned wells across the U.S. We find that $\gt$ 4.6 million people live within 1 km of a documented orphaned well. 35% of the documented orphaned wells are located within 1 km of a domestic groundwater well, yet only 8% of the wells have groundwater quality data within a 1 km radius. Methane emissions from the documented orphaned wells represent approximately 3%–6% of total U.S. methane emissions from abandoned oil and gas wells, but this estimate is based on measurements at $\lt$ 0.03% of U.S. abandoned wells. 91% of the documented orphaned wells overlie formations favorable for geologic storage of carbon dioxide and hydrogen, meaning that orphaned well plugging can reduce leakage risks from future storage projects. Finally, we estimate plugging costs for documented orphaned wells to exceed the $4.7 billion federal funding by 30%–80%, emphasizing the importance of prioritizing federal spending on wells with large remediation benefits. Overall, environmental monitoring data are not extensive enough to quantify risks, especially those related to air and water quality and human health. Plugging orphaned wells can provide opportunities for geologic storage of carbon dioxide and hydrogen and geothermal energy development, thereby facilitating efforts to transition to net-zero energy systems. Our analysis on environmental risks and opportunities of orphaned wells provides a framework that can be used to manage the millions of documented and undocumented orphaned wells in the U.S. and abroad