Access Tubes Research Articles

Spatial and Temporal Distribution of Soil Moisture in Maize Using Frequency Domain Reflectometry Sensor

Field experiment was conducted during kharif 2018, rabi 2018-19 and kharif 2019 at Department of Soil Water Engineering, Dr. NTR College of Agricultural Engineering, Bapatla, Andhra Pradesh to study the spatial and temporal distribution of soil moisture in maize using FDR sensor.The experiment was laid out in split plot design consisting of three irrigation levels (0.6 ETc (I1), 0.8 ETc (I2) and 1.0 ETc (I3)) and four nitrogen levels consisting of fertigation levels (80% RDN (N1), 100% RDN (N2), 120% RDN (N3) and Manual application (N4) on sandy clay loam soil. Water requirement of the maize crop was calculated on the daily basis by using CROPWAT 8.0. Frequency Domain Reflectometry (FDR) Sensor was used to measure soil moisture data by installing 34 access tubes up to a depth of 100 cm with an interval of 10 cm from the soil surface and measured soil water content during crop period. Soil moisture was evaluated for 2.0 lph emitter discharges at 3h after irrigation, 6h after irrigation, 24h after irrigation at emitter, 15 cm from emitter, 30 cm from emitter and 45 cm from emitter for soil moisture in the soil for arriving the best irrigation strategy. The soil water distribution under all drip irrigation treatments indicated that it was relatively high near the dripper and decreased as the distance from the dripper point increased.

Spectral analysis of cross-hole sonic logging data for pile integrity assessment

Ensuring the safety of foundations requires advanced non-destructive testing techniques. Cross-hole sonic logging (CSL) is a widely adopted method for evaluating the integrity of deep foundation elements, such as bored piles, barrettes, and diaphragm walls. This method involves analyzing the propagation time and relative energy of ultrasonic pulses transmitted and registered by probes inserted into pre-installed access tubes. However, in certain cases, standard analyses may not effectively distinguish anomalous signals arising from defects and other factors unrelated to concrete quality. Our study explores the potential of an alternative frequency-domain approach for CSL data analysis. We propose new attributes to quantify ultrasonic signal spectra, including spectrum area, normalized spectrum area, weighted mean frequency, and maximum frequency. These attributes are automatically calculated, eliminating the need for additional data processing time and minimizing the risk of human error. The proposed approach was applied to CSL data collected from two bored piles of 46 m length and successfully identified signals classified as anomalous through standard time-domain analysis. Further research is deemed necessary to fully explore the potential of the frequency-domain approach in enhancing the information content and reliability of CSL pile integrity testing

Characteristics and Mitigation Measures of Candidaauris Infection: Descriptive Analysis from a Quaternary Care Hospital in Saudi Arabia, 2021–2022

ObjectiveTo analyze the characteristics of C. auris cases, and to describe the interventions applied for improving the diagnosis and controlling the transmission.MethodMedical records of C. auris cases reported between January 2021 until June 2022 at King Saud Medical City (KSMC), Riyadh, Kingdom of Saudi Arabia have been reviewed. We analyzed the demographic and clinical characteristics of the cases to illustrate the possible contributing factors with C. auris infection. A multidisciplinary committee has been formulated to investigate the potential source of the outbreak among clusters of cases in the intensive care units (ICU). A bundle of mitigation measures has been applied which was successful to contain the outbreak.ResultsDuring the study period, a total of 129 cases of C. auris were identified, their mean age is 47 ± 22.3 SD, and 72.1% are males. 57% of cases were colonized, all of them were identified through active screening. A number of comorbidities were present including 27.9% were having hypertension, 27.1% with diabetes, 22.5% with COVID-19 and 20.2% with respiratory diseases. The average length of stay before reported positive was 36.23 days. 78.3% of those patients were in the critical care unit, 73.6% with vascular catheter, 88% with urinary catheters and 66.7% with mechanical ventilation. The vast majority of patients were using multiple antibiotics (86%). As per the univariate logistic model, risk factors significantly associated with mortality were (Age, Trauma RTA, ICU, Vascular Access, Foley Catheters, Mechanical Ventilation, Tracheostomy and Endotracheal Tubes) with p values (0.0038, 0.0159, 0.0108, 0.0122, 0.0071, <.0001, 0.0148 and 0.0107), respectively. Multivariate logistic regression showed that having a Foley Catheter was the only statistically significant factor associated with mortality.ConclusionThis retrospective analysis highlights the main characteristics associated with C. auris-infected patients. In addition, it highlights the effectiveness of the bundle of mitigation strategies applied to limit the spread of C. auris in healthcare facilities.

Recognition and Defensive Behavior of Nannotrigona testaceicornis Workers (Lepeletier, 1836) (Hymenoptera, Apidae) in Intra and Inter-colonial Bioassays

Nannotrigona testaceicornis (Lepeletier, 1836) is a stingless bee with wide distribution in the Brazilian territory. Despite its importance in meliponiculture and pollination, there are still few behavioral studies related to the species. The aim of this work was to characterize the recognition and defense behaviors in intraspecific bioassays carried out in N. testaceicornis colonies. Intra and inter-colonial bioassays were carried out with six colonies from different locations. The number of occurrences of each behavioral act, latency measures, and duration of confrontations were quantified. An ethogram with eight behavioral acts and two categories was elaborated. The acceptance rate was significantly higher in intra-colonial confrontations and the rejection rate was higher in inter-colonial confrontations. The rejection process was significantly higher than the acceptance process, which may be related to the specific behavioral repertoire of each process. Results indicate that the presence of an intraspecific intruder triggers an aggressive response from guards positioned in the colony access tube.

Field Evaluation of Conventional and Downhole TDR Soil Water Sensors for Irrigation Scheduling in a Clay Loam Soil

Highlights Soil profile water content derived from Acclima TDR-315™ sensors approximated those from NMM measurements. Soil profile water content from Campbell Scientific SoilVUE™10 sensors grossly underestimated those from the NMM. VWC values from SoilVUE10 sensors were consistently less than those reported by the TDR-315 sensors at all depths. These findings do not support SoilVUE10 use for irrigation scheduling in clay loam soils. Abstract. A field study was performed to evaluate the efficacy of two commercially available time domain reflectometry (TDR) soil water sensors for irrigation scheduling in a clay loam soil near Bushland, Texas. SoilVUE10 (Campbell Scientific Inc., Logan, Utah) and TDR-315 (Acclima Inc., Meridian, Idaho) sensors were installed within 30 cm of neutron moisture meter (NMM) access tubes in a research field planted to corn (Zea mays L) in 2020 and irrigated by a center pivot sprinkler system. Irrigation treatments included 50%, 75%, and 100% of evapotranspiration (ET) replacement with two access tubes installed in each plot, totaling six sensor evaluation sites. Semiweekly measurements with a field-calibrated NMM were used to monitor soil water status and schedule irrigation throughout the growing season. Soil profile water content values integrated over the surface to 1.1-m depth range were derived from SoilVUE10 and vertically distributed arrays of Acclima TDR-315 sensors installed at equivalent depths and were compared with those from NMM data. Average profile soil water contents from the TDR-315 sensors trended well with those from the NMM having mean bias difference (MBD) values of -9.8, -3.1, and 8.4 mm for the 50%, 75%, and 100% treatments, respectively. In contrast, soil profile water content values from the SoilVUE10 sensors grossly underestimated those from the NMM for all irrigation treatments with MBD values of -54.4, -70.5, and -89.8 mm for the 50%, 75%, and 100% treatments, respectively. Comparisons of volumetric water content (VWC) at each of the nine depths common to both electromagnetic sensor types revealed that values from the SoilVUE10 sensors were consistently less than TDR-315 values for all irrigation treatments. Underestimation at the near surface (5 and 10 cm depths) was attributed to loss of soil to electrode contact possibly associated with clay shrinkage during periodic drying following irrigation. Although soil to electrode contact can be problematic at greater depths, the explanation for chronic underestimation of VWC was less obvious except to note that underestimation occurred immediately after installation, which indicated poor electrode-soil contact after installation despite use of manufacturer guidelines and tools. Other possible reasons include challenges for accurate estimation of soil permittivity for a measured permittivity that includes the plastic sensor body. Results from this study suggest vertically distributed arrays of TDR-315 sensors can provide profile water content values adequate for monitoring soil water status for irrigation scheduling in a clay loam soil. The chronic underestimation observed for the SoilVUE10 sensors does not support their use for water resources research and irrigation management and could lead to over irrigation. Additionally, the relatively short 1 m length is less than the rooting depth of many regional crops and thus not capable of determining percolation below the root zone. Keywords: Acclima TDR-315, Campbell Scientific SoilVUE, Irrigation scheduling, Neutron moisture meter, Semi-arid, Soil water sensors, Time domain reflectometry, Volumetric water content.

EVALUATION OF ARTEMISININ CONTENT AS AFFECTED BY SOIL AND WATER MANAGEMENT STRATEGIES UNDER GRAVITY-DRIP IRRIGATION SYSTEM I SAMARU, NIGERIA

ABSTRACT Malaria has been among the dangerous diseases not only in Nigeria but Africa as whole. Artemisia crop has an artemisinin, which is a strong anti- malaria drug. However, despite its importance in curing this disease, it is only produced under rain-fed but hardly produced under irrigation in Nigeria. The experiment consisted of three levels of irrigation water application at 100, 80, and 60% ETo (reference evapotranspiration); two mulch levels (rice straw mulch and no mulch) giving a total number of six treatments, replicated three times, totaling eighteen treatments laid in Randomized Complete Block Design (RCBD). The soil moisture was monitored throughout the crop growing season with access tubes installed at different incremental depth of 0-20 cm, 20-40 cm and 40-60 cm below the soil surface. The artemisinin content was determined in the Faculty of Pharmaceutical Sciences, Ahmadu Bello University, Zaria. The artemisinin content obtained ranges from 0.27 % w/w to 1.84 % w/w. The least artemisinin content was obtained from the treatment with irrigation at 60% ETo with no mulch. While the highest value was obtained with irrigation at 100% ETo with rice straw mulch. The artemisinin content of artemisia annua is affected by water stress. Irrigating the crop fully results in higher artemisinin content of artemisia annua followed by 20 % deficit. The least artemisinin content of artemisia annua was obtained at much water stress of 40 %. The study, recommends a full irrigation could be practiced for effective production of artemisia crop under drip irrigation. However, up to 40 % irrigation water deficit could be applied in areas of high water scarcity. Moreover, since rice straw is cost effective, it is recommended for use as mulching material for the cultivation of artemisia crop under irrigation.

Methods for downhole soil water sensor calibration—Complications of bulk density and water content variations

AbstractDownhole soil volumetric water content (VWC) sensors are used in access tubes to assess the soil water content at multiple depths. If sensor readings are spaced closely enough vertically and are accurate enough, then accurate soil profile water content storage and change in storage can be determined over the depth range of readings, leading to accurate estimates of evapotranspiration (ET) if readings extend to well below the root zone. Even if sensing only covers the active root zone, soil water depletion may be determined well enough to inform irrigation scheduling. While sensor accuracy is dependent on many factors, including the sensor's physical principle of operation, soil‐specific calibration is typically required for good accuracy. In soils with multiple horizons (layers) of different texture, bulk density (BD), or chemical composition, horizon‐specific calibrations may be necessary. We describe methods and equipment used for downhole sensor calibration to typical accuracy of &lt;0.01 m3 m−3 with specific reference to calibration of 10 neutron scattering meters in a soil that required three different horizon‐specific calibrations. Our results contrast with the factory calibration, which would result in a 38‐mm error in water stored in a 1.5‐m deep profile of our soil. We describe variability of measured VWC and BD with depth, distance, and water content and the errors that result from using BD to convert mass basis (g g−1) water content data to VWC data, which can be as much as 35 mm (7.26% underestimation) for soil water storage in a 1.5‐m deep profile of our soil.

Collaborative simulation rotation with integrated cardiothoracic and vascular surgery junior residents accelerates technical skill progression

ObjectiveIntegrated cardiothoracic surgery (CTS) and vascular surgery (VS) residents must achieve operative independence in fewer years compared with residents in traditional training paradigms. Developing a strong foundation early in training from which to build technical skills is of paramount importance. We hypothesized that intensive simulation performed by CTS and VS junior residents would accelerate technical skill progression and improve confidence. MethodsIn July 2021, 7 post-graduate year (PGY)-1 and 5 PGY-2 residents from integrated CTS and VS programs at a single institution participated in a collaborative simulation rotation. Training included low-fidelity vascular anastomoses, high-fidelity cadaver operative simulation, and core surgical tasks. Residents rated confidence levels before and after training. Performance during end-to-end and end-to-side vascular anastomoses (pre- and post-simulation) were evaluated for: respect for tissue, time and motion, needle handling, needle angles, and knot tying. ResultsEnd-to-end anastomosis scores increased from 10.4 to 19 (p < .001); completion times reduced from 10.8 to 8.7 min (p = .02). End-to-side anastomosis scores increased from 11.4 to 14.6 (p < .001); completion time was unchanged at 8.8 vs. 8.9 min. Trainee confidence level increased for these core tasks: knot tying (3.4 vs 4.1, p = .03), end-to-end anastomosis (2.1 vs 3.6, p < .01), end-to-side anastomosis (1.9 vs 3.3, p < .01), Castroviejo needle driver handling (2.7 vs 3.8, p < .01), ultrasound guided vascular access (2.4 vs 3.5, p = .01), bronchoscopy (1.8 vs 3.1, p = .01), and chest tube placement (1.9 vs 3.1, p < .01). ConclusionsDedicated collaborative simulation focusing on technical skills relevant to both CTS and VS trainees accelerates skills progression and increases resident confidence.

Simultaneous side-wall-schlieren and -emission imaging of autoignition phenomena in conventional and constrained-reaction-volume shock-tube experiments

Simultaneous schlieren and emission imaging through the side wall of a round shock tube is reported for application to experimental autoignition studies. A round, optically accessible shock tube featuring windows designed as aberration-corrected cylindrical lenses provides a large side-wall field of view compatible with both emission and schlieren imaging. Autoignition experiments are reported for non-dilute propane–oxygen–argon mixtures (ϕ=1 C3H8 in 21% O2, 79% Ar) at temperatures (T5) spanning the range 1,203–1,438 K and pressures near 1 atm. Experiments are performed using both conventional and constrained-reaction-volume (CRV) filling, allowing for the most detailed comparison to date of ignition dynamics between these two types of experiments. When T5 exceeds 1,290 K, strong ignition is observed to initiate in the immediate proximity of the end wall regardless of the filling strategy. In lower-T5 experiments, mild ignition is observed to initiate spontaneously at remote locations, which often exceeding the imaging FOV in conventional experiments but are constrained within about 5 cm of the end wall in CRV experiments. Measured ignition delay times (IDTs) are compared to predictions from three kinetic mechanisms. IDTs simulated using the San Diego and USC Mech II mechanisms are of the same magnitude as the measurements but exhibit a lower activation energy; the propane submechanism from NUIG 1.1, meanwhile, systematically over predicts observed IDTs by roughly a factor of two. Comparisons are also made between the experimental measurements and predictions from a recently introduced 1-D axial-temperature-gradient model describing remote ignition in shock tubes. Considering the effect of a supposed dT5/dz=150 K/m gradient, the 1-D model functionally predicts the remote ignition observed in T5< 1,290 K experiments and suggests the use of CRV filling may significantly reduce the error introduced into IDT measurements by remote ignition at low-T5 conditions.

Factors Associated With Gastrostomy Tube Complications in Infants With Congenital Heart Disease

IntroductionChildren with congenital heart disease (CHD) often experience feeding intolerance due to aspiration, inability to tolerate feed volume, or reflux within the first few months of life, requiring a surgically placed gastrostomy tube (GT) for durable enteral access. However, complications such as GT dislodgement, cellulitis, and leakage related to GT use are common. GT-related complications can lead to unscheduled pediatric surgery clinic or emergency room (ER) visits, which can be time consuming for the family and increase overall healthcare costs. We sought to identify factors associated with GT complications within 2 wk after GT surgery and 1-y after discharge home following GT placement in infants with CHD. MethodsWe performed a retrospective cohort study using the Society of Thoracic Surgeons database and electronic medical records from a tertiary children's hospital. We identified infants <1 y old underwent CHD surgery followed by GT surgery between September 2013-August 2018. Demographics, pre-operative feeding regimen, comorbidities, and GT-related utilization were measured. Postoperative GT complications (e.g., GT cellulitis, leakage, dislodgement, obstruction, and granulation tissue) within 2 wk after the GT surgery and an unplanned pediatric surgery clinic or ER visit within 1-y after discharge home were captured. Bivariate comparisons and multivariable logistic regression evaluated factors associated with GT complications and unplanned clinic or ER visits. A Kaplan–Meier failure curve examined the timing of ER/clinic visits. ResultsOf 152 infants who underwent CHD then GT surgeries, 66% (N = 101) had postoperative GT complications. Overall, 83 unscheduled clinic visits were identified after discharge, with 37% (N = 31) due to concerns about granulation tissue. Of 137 ER visits, 48% (N = 66) were due to accidental GT dislodgement. Infants who were hospitalized for ≥2 wk after GT surgery had more complications than those discharged home within 2 wk of the GT surgery (40.6% versus 15.7%, P = 0.002). Infants receiving oral nutrition before CHD surgery (38.6% versus 60%, P=<0.001) or with single ventricle defects (19.8% versus 37.3%, P = 0.02) had fewer GT complications. After adjusting for type of cardiac anomaly, infants receiving oral nutrition prior to CHD surgery had a decreased likelihood of GT complications (odds ratio OR 0.46; 95% confidence intervals CI:0.23-0.93). A Kaplan–Meier failure curve demonstrated that 50% of the cohort experienced a complication leading to an unscheduled ER/clinic visit within 6 mo after discharge. ConclusionsUnplanned visits to the ER or pediatric surgery clinic occur frequently for infants with CHD requiring a surgically placed GT. Oral feedings before cardiac surgery associated with fewer GT complications. Prolonged hospitalization associated with more GT complications. Optimizing outpatient care and family education regarding GT maintenance may reduce unscheduled visits for this high-risk, device-dependent infant population.

PCA Benchmark Analysis with ADVANTG3.0.1. and MCNP6.1.1b Codes

The Pool Critical Assembly Pressure Vessel (PCA) benchmark is a well known benchmark in the reactor shielding community which is described in the Shielding Integral Benchmark Archive and Database (SINBAD). It is based on the experiments performed at the PCA facility in the Oak Ridge National Laboratory (ORNL) and it can be used for the qualification of the pressure vessel fluence calculational methodology. The measured quantities to be compared against the calculated values are the equivalent fission fluxes at several experimental access tubes (A1 to A8) in front, behind, and inside the pressure-vessel wall simulator. This benchmark is particularly suitable to test the capabilities of the shielding calculational methodology and cross-section libraries to predict invessel flux gradients because only a few approximations are necessary in the overall analysis. This benchmark was analyzed using a modern hybrid stochastic-deterministic shielding methodology with ADVANTG3.0.1 and MCNP6.1.1b codes. ADVANTG3.0.1 is an automated tool for generating variance reduction (VR) parameters for Monte Carlo (MC) calculations with MCNP5v1.60 code (and higher versions). It is based on the multigroup, discrete ordinates solver Denovo, used for approximating the forward-adjoint transport fluxes to construct VR parameters for the final MC simulation. The VR parameters in form of the weight windows and the source biasing cards can be directly used with unmodified MCNP input. The underlining CADIS methodology in Denovo code was initially developed for biasing local MC results, such as point detector or a limited region detector. The FW-CADIS extension was developed for biasing MC results globally over a mesh tallies or multiple point/region detectors. Both CADIS and FW-CADIS are based on the concept of the neutron importance function, which is a solution of the adjoint Boltzmann transport equation. The equivalent fission fluxes calculated with MCNP are based on several highenergy threshold reactions from international dosimetry libraries IRDF-2002 and IRDFF-2014, distributed by the IAEA Nuclear Data Section. The obtained results show a good agreement with referenced PCA measurements. Visualization of the deterministic solution in 3D was done using the VisIt code from the Lawrence Livermore National Laboratory (LLNL).

Opioid-Sparing Analgesic Effects of Peripheral Nerve Blocks in Percutaneous Nephrolithotomy: A Systematic Review.

Introduction: Multimodal analgesic regimens incorporating peripheral nerve blocks (PNBs) have demonstrated reduced postoperative pain, opioid use, and recovery time in various disease states. However, this remains a subject of limited investigation in the percutaneous nephrolithotomy (PCNL) domain. In the face of an ongoing opioid epidemic and collective push to enhance prescribing stewardship, we sought to examine the potential opioid-sparing effect of PNBs in PCNL. Methods: A systematic review of Embase and PubMed was performed to identify all randomized controlled trials evaluating the use of a PNB with general anesthesia (GA) vs GA alone for pain control following PCNL. Studies evaluating neuraxial (epidural and spinal) anesthesia and those without GA as the control arm were excluded. Results: Seventeen trials evaluating 1,012 procedures were included. Five different blocks were identified and evaluated: paravertebral (n = 8), intercostal nerve (n = 3), quadratus lumborum (n = 2), transversus abdominis plane (n = 1), and erector spinae (n = 3). Nine of 16 (56%) studies observed lower pain scores with PNB use throughout the 24-hour postop period. By comparison, improved pain scores with PNBs were limited to the early (<6 hours) recovery period in five studies and two found no difference. Total analgesic and opioid requirements were significantly higher in the GA control arm in nearly all studies (12/14, 86%). Operative times were similar and there were no differences in rates of intercostal access or nephrostomy tube insertion between study arms in any trial. Conclusions: While greater analgesic use with GA alone likely minimizes or obscures differences in patient-reported pain scores, PNBs may offer a significant opioid-sparing analgesic effect during postoperative recovery after PCNL.

Experimental visualization and characteristics of bubble nucleation during rapid decompression of supercritical and subcooled carbon dioxide

The rapid decompression of sub-cooled and supercritical carbon dioxide was investigated experimentally using schlieren and regular high-speed photography. An optically accessible expansion tube was designed and constructed. A test campaign with initial pressures ranging from 6.45–9.02 MPa and initial temperatures from 297–308 K was performed. High-speed schlieren imagery was used to visualize the decompression waves, evaporation waves, and an oscillatory phase change region present in the blowdown process. The time history of pressures at different locations along the expansion tube were recorded using fast response pressure transducers. Image and pressure signal analyses were performed to extract decompression wave speeds and evaporation wave speeds. Results were compared to analytical models and other experiments reported in the literature. The relationship between pressure undershoot and wave speed to the initial conditions was analysed.

Field performances of energy pile based on the secondary utilization of sonic logging pipes

An energy pile has dual functions of bearing the upper structure load and transferring shallow ground temperature energy. Cross-hole sonic logging (CSL) is used to evaluate the integrity of large-diameter bored piles. CSL test tubes are usually abandoned after integrity tests. A secondary utilization of tubes can be advocated to save resources. In this paper, a new scheme is proposed to connect the bottom end of the access tube in a CSL test to form a new type of loop in the energy pile. A CSL tube is made of galvanized steel pipe (GSP). The thermal and thermomechanical performance of the energy pile with GSP loops and conventional polyethylene (PE) loops is measured by a thermal performance test at the cooling phase. The influence of the modified GSP tubes on the pile integrity can be neglected in the integrity test (CSL test). The heat exchange performance indicates that secondary utilization technology has good prospects. Owing to the discrepancies of different tube materials (thermal conductivity, heat capacity, and thermal coefficient), the heat exchange rate of the energy pile with GSP loops is approximately 26% higher than that of the energy pile with PE loops. The displacements at the pile top with GSP and PE loops after 120 h cooling are 0.15% and 0.083% times the pile diameter, respectively.

The "Big Five" of Invasiveness - the Usefulness of Drains, Probes and Catheters in Colorectal Surgery

The perioperative management of colorectal resections is often dominated by traditional procedures and a strong focus on safety. Evidence-based measures such as those established in Fast Track or ERAS programs, are rarely applied in a standardised manner. As part of elective colorectal surgery, many patients therefore continue to routinely receive central venous access, peridural catheters, urinary catheters, drains and/or gastric tubes ("Big Five" of invasiveness). This article presents the currently available evidence on these measures in colorectal surgery. In addition, results relating to the "Big Five" from the author's own centre are presented. This review shows that the "Big Five" of invasiveness are clinically unnecessary or supported by evidence. In addition, they often impair the patient's function.

Fiber Optic Pressure Measurements Open Up New Experimental Possibilities in Hydrogeology.

Fiber-optic (FO) technology is being used increasingly for measurement methods in a variety of environmental applications. However, FO pressure transducers are rarely used in hydrogeological applications. We review the current state of Fabry-Pérot interferometry-based FO pressure transducers, including their advantages and limitations, as another option for high-resolution pressure- or head-change measurements in conventional or advanced aquifer testing. Resolution and precision specifications of FO transducers meet or exceed commonly used non-FO pressure transducers. Due to their design, FO transducers can be used in small-diameter (inner diameter ≥1/4inch) and continuous multichannel tubing (CMT), sampling points, multilevel packer systems, and Direct Push-based in situ installations and testing. The small diameter of FO transducers provides logistical advantages-especially for tests with monitoring at many zones in a number of wells and/or CMTs (e.g., no reels, placement just below water level in access tubes vs. within isolated zones, reduced weight and volume, small footprint at single point of data acquisition). Principal limitations are small measurement drift that may become evident for tests longer than a few hours, and higher-than-average cost. We present field examples of FO transducer performance in short-term tests with high consistency of acquired data and higher resolution (i.e., capturing significant hydrologic information) compared with commonly used non-FO transducers. Given the above, including advantageous logistical features, FO transducers can open new experimental possibilities in areas of high-resolution three-dimensional (3D) heterogeneity (flow and transport, remediation, critical zones); 3D fracture networks and fundamental hydromechanical behavior; complex 3D flow and leak detection (mines, dams, repositories, geothermal systems).

Nondestructive Evaluation of Drilled Shaft Construction Anomalies Using Full Waveform Tomography of Simulated Crosshole Measurements

Construction of drilled shafts for transportation infrastructure presents quality assurance challenges related to structural anomalies, including voids and degraded concrete. Efforts to evaluate anomalies often use stress-wave non-destructive testing (NDT) techniques such as the crosshole sonic logging (CSL) method. CSL relies on the propagation of stress waves between access tubes inserted alongside the reinforcement cage. Differences in travel time and amplitudes can be used to estimate concrete quality within the source-receiver ray paths. Crosshole tomography (CT) advances this approach further and models ray paths to solve an inverse problem based on first arrival times. However, both stress-wave methods cannot typically evaluate anomalies smaller than 10% to 15% of the shaft cross sectional area. Recent advances in wave propagation modeling have led to the development of full waveform inversion (FWI) approaches. FWI attempts to generate a more detailed tomographic model that matches the entire waveform recordings. This paper presents findings from a numerical study where full waveform tomography was performed on a portion of a drilled shaft with a structural anomaly. Crosshole stress-wave propagation was simulated using a spectral element method (SEM) forward modeler. The resulting waveforms were then used as inputs into a CT travel-time inversion algorithm using ray-path modeling and into a FWI algorithm using the entire recorded signals. The results highlighted that FWI estimated concrete velocities and the geometry of the anomaly more accurately than CT in the idealized numerical model. This was the case even though information from more sources and receiver pairs was used for the CT inversion.

QUALITY ASSURANCE OF DIAPHRAGM AND PILE WALLS BY GEOPHYSICS

Underground structures like diaphragm and pile walls are constructed to organize waterproof curtains, protect pit sides, and transfer loads from the structures. Violations of the construction technological process can lead to the formation of defects. To prevent adverse consequences, before excavation, it is necessary to control the integrity of the slurry walls using non-destructive geophysical methods. A review of geophysical slurry wall quality control methods based on the excitation and registration of physical fields through access tubes installed in the reinforcement cage, in wells drilled near the structure or on the surface of the structure, is presented. The main capabilities and limitations of the methods are given. Cross-hole ultrasonic logging was used to study the section of the slurry wall during the construction of the Moscow Metro station. The results of parallel soundings made it possible to identify anomalous zones, interpreted as defects. The geometric dimensions of one of the major defects were refined by ultrasonic tomography. For the first time in Russian testing practice, thermal integrity profiling was applied to study the diaphragm wall at the base of a residential building. The results of temperature monitoring during the concrete hardening are presented. According to the method, a major flaw, excess of the design mark of the wall bottom and bulging of the structure were revealed. The results of thermal integrity profiling were verified by ultrasonic logging. The combined use of thermal and ultrasonic methods can be recommended as a reliable tool for integrity testing of diaphragm and pile walls. To carry out the measurements, the access tubes shall be included in the reinforcement cage of the structure at the design stage.

Estimating nitrogen inputs, storage, and exports for a small watershed in the upper Mississippi river basin, USA

Nitrogen contributions to the Gulf of Mexico hypoxic zone from agriculture watersheds are well documented. Beargrass creek watershed a 5,985hectare agriculturally dominated watershed in northern Indiana was instrumented to collect water quality data. A nitrogen budget was developed to account for net input and export of nitrogen from the watershed. Inputs consisted of fertilizer application, soil mineralization, and atmospheric deposition. Exports consisted of nitrogen removal in grain and stream exportation. Water quality testing at two gage stations, fourteen access tubes, and nine drainage tiles determined where excess nitrogen was stored. Nitrogen inputs was estimated at 1,004,213kg/year or 168 kg/ha/year in 2015. Total nitrogen exports accounted for 860,250kg/ha or 144kg/ha/year: with 30% of the applied nitrogen removed by Beargrass Creek through baseflow, tile flows, and storm event runoff.

Critical procedure performance in pediatric patients: Results from a national emergency medicine group

Study objectiveWe sought to examine the frequency of pediatric critical procedures performed in a national group of emergency physicians. MethodsWe performed a retrospective analysis of an administrative billing and coding dataset for procedural performance documentation verification from 2014 to 2018. We describe and compare incident rates of pediatric (age <18 years) patient critical procedure performance by emergency physicians in general emergency departments (EDs), pediatric EDs, and freestanding ED/urgent care centers. Critical procedures were endotracheal intubation, electrical cardioversion, central venous placement, intraosseous access, and chest tube insertion. ResultsAmong 2290 emergency physicians working in 186 EDs (1844 working in 129 general EDs, 125 in 8 pediatric EDs, and 321 in 49 freestanding EDs/urgent cares), a total of 2233 pediatric critical procedures were performed during the study period. Many physicians at general EDs and freestanding EDs/urgent cares performed zero pediatric procedures per year (53.9% and 89% respectively). Per 1000 ED visits seen (All patient ages), physicians working in general EDs performed fewer pediatric critical procedures than physicians in pediatric EDs (0.12/1000 visits vs 0.68/1000 visits; rate difference = 0.56, 95% confidence interval [CI] 0.51–0.61). Per 1000 clinical hours worked, physicians working in general EDs performed 0.26 procedures compared to 1.66 for physicians in pediatric EDs (rate difference = 1.39; 95% CI 1.27–1.52). ConclusionPediatric critical procedures are rarely performed by emergency physicians and are exceedingly rare in general EDs and freestanding EDs/urgent cares. The rarity of performance of these skills has implications for ED pediatric readiness.