Net Extraction Research Articles

Reduced trans-myocardial extraction of endothelin-1 in cardiac allograft vasculopathy

Abstract Introduction Cardiac allograft vasculopathy (CAV) is a major cause of graft failure due to microvascular dysfunction and ischaemia following heart transplant. Endothelin-1 (ET-1) is an endothelium derived vasoconstrictor peptide with multiple adverse effects including vascular smooth muscle proliferation and pro-inflammatory signalling. Elevated circulating ET-1 has been associated with accelerated CAV. We assessed the trans-myocardial gradient (TMG: coronary sinus minus coronary artery concentration: negative=extraction, positive=secretion) of ET-1 in heart transplant patients to determine correlations with angiographic, Intravascular Ultrasound (IVUS) and Optical Coherence Tomography (OCT) features of CAV. Methods 23 patients underwent invasive coronary angiography, 3-vessel grey scale IVUS (Opticross, 60mHz, Boston Scientific) and OCT (Dragonfly, Abbott Vascular) to define morphological features of vasculopathy 18±3 months post-transplant. Paired blood samples were obtained from the guide catheter and coronary sinus at the time of coronary imaging. Plasma was analysed using specific enzyme-linked immunosorbent assay for ET-1 peptide quantification. Survival was determined 98±5 months after initial assessment. Results ET-1 TMG distribution was mostly in the negative range reflecting net extraction across the coronary vascular bed (median [IQR]: -0.23 [-0.54, -0.02] pg/ml). However, vessels with more severe CAV demonstrated significantly more positive TMG i.e. less ET-1 trans-myocardial extraction (IVUS Stanford Grade IV: -0.05 [-0.21, 0.13] pg/ml versus Stanford Grade I-III: -0.31 [-0.64, -0.11] pg/ml, p = 0.01). ET-1 TMG was positively correlated with mean intimal thickness on both IVUS and OCT (IVUS: Kendall’s tau-b = 0.254, p=0.02 and OCT: Kendall’s tau-b = 0.344, p<0.0001). Patients who died had net ET-1 secretion compared with surviving patients (died: 0.21 [0.19 - 0.24] versus surviving: -0.28 [-0.52, -0.17], p = 0.01). Conclusions In heart transplant patients, coronary arteries with more intimal thickening had less trans-myocardial extraction, and more secretion of ET-1. ET-1 secretion in CAV may mediate the distal microvascular dysfunction commonly seen in this condition. These findings suggest a rationale for testing ET-1 receptor antagonists as a treatment for CAV.ET-1 TMG and IVUS Stanford Grade of CAVET-1 TMG and OCT derived MIT

A tragedy of the commons case study: modeling the fishers king crab system in Southern Chile.

Illegal fishing in small-scale fisheries is a contentious issue and resists a straightforward interpretation. Particularly, there is little knowledge regarding cooperative interactions between legal and illegal fishers and the potential effects on fisheries arising from these interactions. Taking the Chilean king crab (Lithodes santolla; common name centolla) fishery as a case study, our goal is twofold: (i) to model the effect of illegal-legal fishers' interactions on the fishery and (ii) analyze how management and social behavior affect fishery's outcomes. We framed the analysis of this problem within game theory combined with network theory to represent the architecture of competitive interactions. The fishers' system was set to include registered (legal) fishers and unregistered (illegal) fishers. In the presence of unregistered fishers, legal fishers may decide to cooperate (ignoring the presence of illegal fishers) or defect, which involves becoming a "super fisher" and whitewashing the captures of illegal fishers for a gain. The utility of both players, standard fisher and super fisher depend on the strategy chosen by each of them, as well as on the presence of illegal fishers. The nodes of the network represent the legal fishers (both standard and super fishers) and the links between nodes indicate that these fishers compete for the resource, assumed to be finite and evenly distributed across space. The decision to change (or not) the adopted strategy is modeled considering that fishers are subjected to variable levels of temptation to whitewash the illegal capture and to social pressure to stop doing so. To represent the vital dynamics of the king crab, we propose a model that includes the Allee effect and a term accounting for the crab extraction. We found that the super fisher strategy leads to the decrease of the king crab population under a critical threshold as postulated in the tragedy of the commons hypothesis when there are: (i) high net extraction rates of the network composed of non-competing standard fishers, (ii) high values of the extent of the fishing season, and (iii) high density of illegal fishers. The results suggest that even in the presence of super fishers and illegal fishers, the choice of properly distributed fishing/closure cycles or setting an extraction limit per vessel can prevent the king crab population from falling below a critical threshold. This finding, although controversial, reflects the reality of this fishery that, for decades, has operated under a dynamic in which whitewashing and super fishers have become well established within the system.

Mine and Lattice Web Data using NLP

This Paper will be an exercise in net extraction, natural language processing (NLP), and named entity recognition (NER). For the NLP, we will primarily be using the open-supply Python libraries NLTK and Spacy. This paper is meant to be a demonstration of a use-case for net extraction and NLP, now no longer a complete novice educational to the use of both techniques. We extricated joins from a web page, at that point utilized those joins to extricate indeed more substance from the internet location. We utilized that substance to at that point extricate and upgrade that data utilizing outside APIs, ML clustering calculations, and NLP.

Coordinated slag Disposal From Horizontal Boreholes During Hydraulic Cutting Based on Two-Phase Flow Theory

The purpose of the study is to explore the mechanism of coordinated slag disposal in the hydraulic cutting process, ensure the safety implementation of the hydraulic cutting operation and increase the success rate of hydraulic cutting. In the ultra-high pressure hydraulic cutting technique, the method for determining the cutting pressure is ambiguous, the coordination mechanism of various factors (including cutting pressure and coal-dropping speed) lingers unclarified; the slag disposal mechanism during hydraulic cutting is inexplicit. Aiming at these problems, a model for coordinated slag disposal during hydraulic cutting based on coal‐water two-phase flow was established. The critical flow velocity in the moving laminar flow regime is taken as that during the coordinated slag disposal from boreholes. The relationship curve between the coal-dropping speed and cutting pressure under different Protodyakonov coefficients of coal seams was obtained. Hence, the model for coordinated slag disposal during hydraulic cutting was established; the selection interval of reasonable pressure for coordinated slag disposal during hydraulic cutting was determined. The reasonable cutting pressure for slag disposal in coal seams with a Protodyakonov coefficient of 0.48 was determined as about 80 MPa. During the cutting test, the average net gas extraction from the boreholes for hydraulic cutting was 4.5 times larger than that from the conventional boreholes. Furthermore, the gas permeability coefficient of the boreholes for hydraulic cutting increased by 25 times; the effective extraction radius was more than doubled. It indicated that the model for reasonably selecting the cutting pressure based on the coordinated slag disposal theory can effectively guide the selection of the cutting pressure on site. While solving various problems occurring in the hydraulic cutting process on site, the model can be used to improve the cutting effect, which provides a theoretical basis for reasonably selecting the pressure during ultra-high pressure hydraulic cutting.

Gas extraction technology and application of near horizontal high directional drilling

In order to solve the problem of gas accumulation in the upper corner caused by large gas emission due to high mining intensity in the fully mechanized top coal caving face of Wangjialing coal mine, we used numerical simulation method combined with the key stratum layer control theory to study the roof caving trend and development law of inclined mining fissure. Then we analyzed the evolution process of goaf fissure with the advance of the working face and the development height of roof fissure. Finally, we got the best hole layout position and drilling structure of near horizontal high-level directional long drilling. The practice indicates that we achieved nice gas extraction effect by setting near horizontal high-level directional long drilling borehole according to the above research results. The maximum net extraction volume of a single borehole is 2.10 m3/min, the maximum extraction volume fraction is 31.39%, and the total net amount of gas extracted from the four boreholes under construction is 289900 m3. The gas concentration in the upper corner of the working face decreased to 0.46% during extraction, and the problem of gas overrun in the upper corner was effectively solved.

Performance Comparison of H2O and CO2 as the Working Fluid in Coupled Wellbore/Reservoir Systems for Geothermal Heat Extraction

CO2 is considered as a novel heat-transmission fluid for extracting geothermal energy from enhanced geothermal systems (EGS), attributed to its high compressibility, expansivity and low viscosity in comparison to water. In order to compare the performance of CO2 and H2O as the working fluid in EGS, a classical five-spot model based on the geologic and geothermal conditions at the Songliao Basin, China, was constructed. Results obtained from the coupled wellbore/reservoir model revealed that the net heat extraction and flow rate are greater for CO2 than for H2O at a fixed operation pressure difference between the injection and production wellheads. However, the wellhead temperature is far lower for CO2 than for H2O due to the strong Joule–Thomson effect of CO2 in the wellbore. Moreover, a stronger pressure change in the wellbore is observed by using CO2, attributed to the gravity and high flow velocity of CO2; this pressure change induces a drop in the frictional pressure. For CO2, the enthalpy change in the wellbore is mainly contributed by the gravitational potential, while for H2O, it is contributed by the gravitational potential and lateral heat exchange. The heat extraction performance depends on the operation pressure difference and injection temperature for H2O-based EGS, while it depends on the wellhead pressures of both the injection and production wells as well as the injection temperature for CO2-based EGS. A high operation pressure is favorable for improving the heat extraction performance (especially the production temperature) for CO2. With the temperature drop limitation at the downhole of the production well, the heat extraction performance is better by using H2O than that by using CO2 as the working fluid. However, the low-power consumption for maintaining fluid circulation demonstrates the application potential of CO2-based EGS.

DEEP CONVOLUTIONAL NEURAL STRATEGY FOR DETECTION AND PREDICTION OF MELANOMA SKIN CANCER

The research work has focused on detection and prediction of melanoma which is done by subjecting to features extraction, where the features of an image consisting of melanoma regions are detected by analysis and this analysis is done by considering the features like color and texture-based features learning strategy. These features are extracted by combining color and texture-based features extraction with deep convolutional features representation learning strategy. The colors of images are extracted by representing the colors of different channels into red, green and blue channel information. The combination of texture features extraction with color-based features extraction in addition to Alex net features extraction learning has made the system more robust and efficient toward the segmentation and classification of images. Further, the erected method involves convoluting the features of extracted information with color and texture-based method which has led our system to full convolution neural networks with images features extraction. The melanoma is detected and segmented with watershed segmentation, these segmented features are subjected to the proposed features extraction method, where the features are extracted by combining the methods of texture with color-based information. These colors are made available to the proposed method by analyzing the regions of melanoma images. The erected method does the task of features extraction by Weber law descriptors in combination with red, green, blue channels information extracted from features representation learning. The proposed method has yielded an accuracy of 94.12% of segmentation accuracy and a classification accuracy of 94.32% with respect to various other classification techniques.

A Study of Availability and Utilization of Water Resources in Punjab

While water is renewable, only a finite amount of it is available. Rapid urbanization, industrial development, and growth in food demand contribute to the shortage of freshwater in many countries. The limited availability of surface water and its uneven distribution in time and space has increased the dependence on groundwater (GW) in Punjab. Its irrigation development is characterized by excessive extraction of GW to meet the crop water requirements for ensuring the country’s self-reliance in food. GW development guided by populist political pronouncements has contributed to serious environmental and ecological concerns. The paper, using the GW resource estimation methodology-2015, assesses the net annual replenish able GW availability (21.58 billion cubic meters) and GW extraction (35.78 billion cubic meters), and thus a stage of GW extraction of 166%. It analyses the impact of continuous GW mining on the long-term behaviour of water table. Considering the declining availability of surface water under climate change, it is a high time to study the emerging GW scenario more scientifically and prescribe a policy framework for the future.

Evaluation of the performance of multiple-well hydraulic barriers on enhancing groundwater extraction in a coastal aquifer

Hydraulic barriers using either two or three injection wells are studied analytically to evaluate their performance on improving groundwater extraction in a coastal aquifer under the threat of seawater intrusion. The multiple well system is operated by extracting fresh groundwater through a landward well and partially reinjecting into the aquifer through two or three wells located parallel to the coastline and between the interface toe and the extraction well. We found that with appropriate well locations and pumping rates, the multiple-well system could outperform a single extraction well in terms of net extraction rate, which is up to 90% higher for an aquifer with a thickness of 20 m, hydraulic conductivity of 10 m/d, and freshwater influx of 0.24 m2/d. Sensitivity analyses reveal that the monotonicity of the maximum net extraction rate is determined by the total injection rate. In specific, when the total injection rate is fixed, the maximum net extraction rate is a non-monotonic function of the distance between the injection well and the coastline and the distance between two injection wells, resulting in a global maximum. When the total injection rate is not fixed, by contrast, the maximum net extraction rate depends on the total injection rate, and a larger total injection rate leads to a larger maximum net extraction rate. By using different injection rates for side and middle injection wells of the three-injection-well hydraulic barrier, the maximum net extraction rate could be further improved, depending on the distance between the two injection wells. Analytical analyses can provide initial guidance for the design of a multiple-well system in coastal aquifers with the purpose of obtaining enhanced extraction under the threats of seawater intrusion.

2193 Role of Endoscopy in Bouveret Syndrome

INTRODUCTION: Biliodigestive fistula is a rare complication of cholelithiasis which can lead to gallstone ileus. The gallstone after passing into GI tract is eliminated in 85 % of the cases through the feces or vomitus. However in 15 % of the cases it gets entrapped in the GI tract most commonly in the terminal ileum. We describe a case of an elderly patient who presented with Bouveret syndrome secondary to impaction of the biliary calculus in the first part of duodenum. CASE DESCRIPTION/METHODS: A 91 yo M presented to the hospital with one week history of nausea, vomiting and abdominal pain. He was noted to have right upper quadrant abdominal tenderness. Liver function tests were unremarkable. CT abdomen with oral contrast showed findings concerning for gastric outlet obstruction secondary to large lamellated gallstone along with a choledochoduodenal fistula. An upper GI endoscopy was done which showed a large immobile gallstone obstructing the first part of duodenum. An attempt to remove the stone endoscopically by various techniques including mechanical lithotripsy and net extraction was unsuccessful. A 7 cm gallstone partially contained in the gallbladder and extending to the duodenum was then successfully removed by open partial cholecystectomy with duodenal extraction followed by choledochoduodenal fistula repair. Patient recovered well without any complications after the surgery. DISCUSSION: Gallstone impaction in the duodenum and pylorus is extremely rare and can lead to gastric outlet obstruction, a condition known as Bouveret syndrome. Bouveret syndrome needs to be managed in a timely fashion. Clinically patients with this condition present with nausea, vomiting and abdominal pain. History of recent bouts of jaundice and biliary colic is seen in up to 70% of the patients. Rarely patients can present with hematemesis secondary to duodenal or celiac artery erosion. CT abdomen with contrast is the imaging of choice. Medium sized mobile stone in the duodenum can be successfully managed endoscopically by lithotripsy or net extraction. However when there is an immobile large calculus, endoscopy often fails and surgical extraction of the stone needs to be done to relieve the obstruction. Nevertheless considering the higher mortality associated with surgery, endoscopic removal of the calculus should be attempted first.

Mono- and di-glucoside anthocyanins extraction during the skin contact fermentation in hybrid grape varieties

In this work, the anthocyanins’ profile of two hybrid grape varieties—Cabernet Carbon and Prior—grown in two experimental plots in Trentino (Northern Italy) was investigated during 2016 and 2017 harvests. The focus was on the mono- and di-glycoside anthocyanins extraction during the fermentative maceration. It was optimized an HPLC-DAD method, which allows the separation and quantification of mono- and di-glucoside anthocyanin forms (non-esterified, acetylated, and p-coumaroylated) in a single chromatographic run. Furthermore, an HPLC-DAD/HQOMS approach was used to confirm the compound identification. The skin contact fermentation was conducted for 7 days at 24 °C, punching down manually the cap twice a day. Must samples were collected every 24 h. As expected, every anthocyanin showed an initial net extraction phase described by a first-order kinetic, followed by a decrease until the end of the maceration. The analysis of the accumulation rate showed a faster increase of the di-glucoside anthocyanins concentration compared to the corresponding mono-glucoside, due to their richness in the initial grapes. Moreover, the di-glucosides concentration at the end of the alcoholic fermentation underwent a three times minor percentage decrease with respect to the maximum reached. This paper intend to improve the knowledge of the kinetics of each anthocyanin form during the maceration step, providing information about the behavior of di-glucoside compounds, never investigated before in terms of accumulation and percentage decrease.

Surgical Aspects of Liver Transplantation and Domino Liver Transplantation in Maple Syrup Urine Disease: Analysis of 15 Donor-Recipient Pairs.

Liver transplantation (LT) has been shown to be a feasible treatment in patients with severe forms of maple syrup urine disease (MSUD). Because of a sufficient extrahepatic enzyme activity in non-MSUD individuals, the organ of MSUD patients can be used as a domino graft. We performed a retrospective data collection of all LTs for MSUD carried out at the University Medical Center Hamburg-Eppendorf (2016-2018). Moreover, data from all consecutive domino LTs of the MSUD grafts either transplanted at our institution or allocated to other transplant centers were analyzed. During the study period, 15 LTs in MSUD patients were performed (12 children, 3 adults; median age, 10.9years; range, 0.3-26.1years). Biliary complications occurred in 20%, and 13.3% suffered from bleeding complications. No further surgical problems occurred. At present, all MSUD patients are alive with a well-functioning liver graft and on an unrestricted diet. In total, 14 consecutive domino LTs were performed. No surgical complications requiring intervention occurred. One patient died because of HCC relapse, and all other patients are alive with good liver graft function. In conclusion, the use of MSUD livers as domino grafts is safe and allows application of LT in MSUD patients without net extraction of a liver graft from the limited donor pool.

Information ratchets exploiting spatially structured information reservoirs.

Fully mechanized Maxwell's demons, also called information ratchets, are an important conceptual link between computation, information theory, and statistical physics. They exploit low-entropy information reservoirs to extract work from a heat reservoir. Previous models of such demons have either ignored the cost of delivering bits to the demon from the information reservoir or assumed random access or infinite-dimensional information reservoirs to avoid such an issue. In this work we account for this cost when exploiting information reservoirs with physical structure and show that the dimensionality of the reservoir has a significant impact on the performance and phase diagram of the demon. We find that for conventional one-dimensional tapes the scope for work extraction is greatly reduced. An expression for the net-extracted work by demons exploring information reservoirs by means of biased random walks on d-dimensional, Z^{d}, information reservoirs is presented. Furthermore, we derive exact probabilities of recurrence in these systems, generalizing previously known results. We find that the demon is characterized by two critical dimensions. First, to extract work at zero bias the dimensionality of the information reservoir must be larger than d=2, corresponding to the dimensions where a simple random walker is transient. Second, for integer dimensions d>4 the unbiased random walk optimizes work extraction corresponding to the dimensions where a simple random walker is strongly transient.

Long-term phosphorus fertilization of wheat, soybean and maize on Mollisols: Soil test trends, critical levels and balances

Abstract Few reports have compared the P critical level between different crops under equivalent growing conditions and the impact of P balance and P fertilization practices on the long term dynamics of soil available P. The objectives of this study were: i) to determine and compare, under similar field conditions, the P critical values for soybean, maize and wheat; and ii) to evaluate the effect of long-term application of P fertilizer on P balance and soil-test P. Results from a long-term experiment (2000/01 and 2013/14) involving soybean, maize and wheat crops in five experimental sites located at the Pampean Region (Argentina) were analyzed. Phosphorus levels included a −P treatment without P application and a +P treatment with continuous P fertilization (annual average 37 kg P ha−1). The critical Bray-P thresholds were 14.3, 12.5 and 19 mg kg−1 for soybean, maize and wheat, respectively. The rate of decline of the Bray-P pool in the −P treatments was described by an exponential decay function common to the five study sites. Obtained results indicated that a net extraction of 327 kg P per hectare is needed to reduce their initial Bray-P values ​​by half, regardless of the initial soil Bray-P value. The soils fertilized with P showed a significant and linear increase in Bray-P. It was possible to fit a single function after pooling the data of the five sites. This combined function indicated that 3.2 kg P ha−1 were necessary to increase Bray-P in 1 mg kg−1. Obtained data on crop P critical levels and rates at which soil-test P declines or increases according to the P balance constitutes a useful tool for sustainable use of P resources in Mollisols and related soil units. They can help to monitor future changes of soil P levels and to estimate the P demand of croplands.

Environmental flows in hydro-economic models

The protection of environmental flows, as a management objective for a regulating agency, needs to be consistent with the aquifer water balance and the degree of resource renewability. A stylized hydro-economic model is used where natural recharge, which sustains environmental flows, is considered both in the aquifer water budget and in the welfare function as ecosystem damage. Groundwater recharge and the associated natural drainage may be neglected for aquifers containing fossil water, where the groundwater is mined. However, when dealing with an aquifer that constitutes a renewable resource, for which recharge is not negligible, natural drainage should explicitly appear in the water budget. In doing so, the optimum path of net extraction rate does not necessarily converge to the recharge rate, but depends on the costs associated with ecosystem damages. The optimal paths and equilibrium values for the water volume and water extraction are analytically derived, and numerical simulations based on the Western La Mancha aquifer (southwest Spain) illustrate the theoretical results of the study.

Replenishing an unconfined coastal aquifer to control seawater intrusion: Injection or infiltration?

AbstractIn this study, we compare the performances of well injection and pond infiltration in controlling seawater intrusion in an unconfined coastal aquifer through two scenario groups: (1) a single injection well versus an elliptic infiltration pond and (2) an injection‐extraction well pair system versus an elliptic infiltration pond‐extraction well system. Comparison is based on quantitative indicators that include the interface toe location, saltwater volume, and maximum net extraction rate (for scenario 2). We introduce a method to determine the maximum net extraction rate for cases where the locations of stagnation points cannot be easily derived. Analytical analysis shows that the performances of injection and infiltration are the same, provided that the pond shape is circular. The examination of scenario group 1 suggests that the shape of the infiltration pond has a minor effect on the interface toe location as well as the reduction in the saltwater volume, given the same total recharge rate. The investigation of scenario group 2 indicates, by contrast, that the maximum net extraction rate increases significantly with the increasing ratio of b to a, where a and b are semiaxes of the ellipse parallel and perpendicular to the coastline, respectively. Specifically, for a typical aquifer assumed, an increase of 40% is obtained for the maximum net extraction when b/a increases from 1/200 to 200. Despite that the study is based on a simplified model, the results provide initial guidance for practitioners when planning to use an aquifer recharge strategy to restore a salinized unconfined coastal aquifer.

Thyroxine (T4) Transfer from Blood to Cerebrospinal Fluid in Sheep Isolated Perfused Choroid Plexus: Role of Multidrug Resistance-Associated Proteins and Organic Anion Transporting Polypeptides.

Thyroxine (T4) enters the brain either directly across the blood–brain barrier (BBB) or indirectly via the choroid plexus (CP), which forms the blood–cerebrospinal fluid barrier (B-CSF-B). In this study, using isolated perfused CP of the sheep by single-circulation paired tracer and steady-state techniques, T4 transport mechanisms from blood into lateral ventricle CP has been characterized as the first step in the transfer across the B-CSF-B. After removal of sheep brain, the CPs were perfused with 125I-T4 and 14C-mannitol. Unlabeled T4 was applied during single tracer technique to assess the mode of maximum uptake (Umax) and the net uptake (Unet) on the blood side of the CP. On the other hand, in order to characterize T4 protein transporters, steady-state extraction of 125I-T4 was measured in presence of different inhibitors such as probenecid, verapamil, BCH, or indomethacin. Increasing the concentration of unlabeled-T4 resulted in a significant reduction in Umax%, which was reflected by a complete inhibition of T4 uptake into CP. In fact, the obtained Unet% decreased as the concentration of unlabeled-T4 increased. The addition of probenecid caused a significant inhibition of T4 transport, in comparison to control, reflecting the presence of a carrier mediated process at the basolateral side of the CP and the involvement of multidrug resistance-associated proteins (MRPs: MRP1 and MRP4) and organic anion transporting polypeptides (Oatp1, Oatp2, and Oatp14). Moreover, verapamil, the P-glycoprotein (P-gp) substrate, resulted in ~34% decrease in the net extraction of T4, indicating that MDR1 contributes to T4 entry into CSF. Finally, inhibition in the net extraction of T4 caused by BCH or indomethacin suggests, respectively, a role for amino acid “L” system and MRP1/Oatp1 in mediating T4 transfer. The presence of a carrier-mediated transport mechanism for cellular uptake on the basolateral membrane of the CP, mainly P-gp and Oatp2, would account for the efficient T4 transport from blood to CSF. The current study highlights a carrier-mediated transport mechanism for T4 movement from blood to brain at the basolateral side of B-CSF-B/CP, as an alternative route to BBB.

Oscillatory hydraulic testing as a strategy for NAPL source zone monitoring: Laboratory experiments

Non-aqueous phase liquids (NAPLs) have a complex mode of transport in heterogeneous aquifers, which can result in pools and lenses of NAPLs (the “source zone”) that are difficult to detect and can cause long-term contamination via slow dissolution into groundwater (the “dissolved plume”). Characterizing the extent and evolution of NAPL contamination within the source zone is a useful strategy for designing and adapting appropriate remedial actions at many contaminated sites. As a NAPL flows into a given aquifer volume, the effective hydraulic conductivity (K) and specific storage (Ss) of the volume changes associated with the viscosity and compressibility of the impinging fluid, meaning that NAPL movement may be detectable with hydraulic testing. Recently, the use of oscillatory pumping tests – in which sinusoidal pumping variations are implemented and oscillatory pressure changes are detected at monitoring locations – has been suggested as a low-impact hydraulic testing strategy for characterizing aquifer properties (Cardiff et al., 2013; Zhou et al., 2016). Here, we investigate this strategy in an experimental laboratory sandbox where dyed vegetable oil is injected and allowed to migrate as a NAPL. Initial qualitative analyses demonstrate that measurable changes in pressure signal amplitude and phase provide clear evidence for NAPL plume emplacement and migration. Using the approach developed in Zhou et al. (2016), we then apply tomographic analyses to estimate the location of effective K changes (representing fluid changes) and their movement throughout time. This approach provides a method for monitoring ongoing NAPL movement without net extraction or injection of fluid, making it advantageous in field remediation applications.

Resonant Generation and Energetics of Wind-Forced Near-Inertial Motions in a Geostrophic Flow

AbstractA slab mixed layer model and two-dimensional numerical simulations are used to study the generation and energetics of near-inertial oscillations in a unidirectional, laterally sheared geostrophic current forced by oscillatory winds. The vertical vorticity of the current ζg modifies the effective Coriolis frequency , which is equivalent to the local resonant forcing frequency. In addition, the resonant oscillatory velocity response is elliptical, not circular, because the oscillation periodically exchanges energy with the geostrophic flow via shear production. With damping, this energy exchange becomes permanent, but its magnitude and sign depend strongly on the angle of the oscillatory wind vector relative to the geostrophic flow. However, for a current forced by an isotropic distribution of wind directions, the response averaged over all wind angles results in a net extraction of energy from the geostrophic flow that scales as the wind work on the inertial motions times (ζg/f)2 for ζg ≪ f. For ζg ~ f, this sink of geostrophic kinetic energy preferentially damps flows with anticyclonic vorticity and thus could contribute toward shaping the positively skewed vorticity distribution observed in the upper ocean.

A century of oil-field operations and earthquakes in the greater Los Angeles Basin, southern California

Most of the seismicity in the Los Angeles Basin (LA Basin) occurs at depth below the sediments and is caused by transpressional tectonics related to the big bend in the San Andreas fault. However, some of the seismicity could be associated with fluid extraction or injection in oil fields that have been in production for almost a century and cover ∼ 17% of the basin. In a recent study, first the influence of industry operations was evaluated by analyzing seismicity characteristics, including normalized seismicity rates, focal depths, and b-values, but no significant difference was found in seismicity characteristics inside and outside the oil fields. In addition, to identify possible temporal correlations, the seismicity and available monthly fluid extraction and injection volumes since 1977 were analyzed. Second, the production and deformation history of the Wilmington oil field were used to evaluate whether other oil fields are likely to experience similar surface deformation in the future. Third, the maximum earthquake magnitudes of events within the perimeters of the oil fields were analyzed to see whether they correlate with total net injected volumes, as suggested by previous studies. Similarly, maximum magnitudes were examined to see whether they exhibit an increase with net extraction volume. Overall, no obvious previously unidentified induced earthquakes were found, and the management of balanced production and injection of fluids appears to reduce the risk of induced-earthquake activity in the oil fields.