Median Displacement Research Articles

Quantitative classification evaluation model for tight sandstone reservoirs based on machine learning

Tight sandstone reservoirs are a primary focus of research on the geological exploration of petroleum. However, many reservoir classification criteria are of limited applicability due to the inherent strong heterogeneity and complex micropore structure of tight sandstone reservoirs. This investigation focused on the Chang 8 tight reservoir situated in the Jiyuan region of the Ordos Basin. High-pressure mercury intrusion experiments, casting thin sections, and scanning electron microscopy experiments were conducted. Image recognition technology was used to extract the pore shape parameters of each sample. Based on the above, through grey relational analysis (GRA), analytic hierarchy process (AHP), entropy weight method (EWM) and comprehensive weight method, the relationship index Q1 between initial productivity and high pressure mercury injection parameters and the relationship index Q2 between initial productivity and pore shape parameters are obtained by fitting. Then a dual-coupled comprehensive quantitative classification prediction model for tight sandstone reservoirs was developed based on pore structure and shape parameters. A quantitative classification study was conducted on the target reservoir, analyzing the correlation between reservoir quality and pore structure and shape parameters, leading to the proposal of favourable exploration areas. The research results showed that when Q1 ≥ 0.5 and Q2 ≥ 0.5, the reservoir was classified as type I. When Q1 > 0.7 and Q2 > 0.57, it was classified as type I1, indicating a high-yield reservoir. When 0.32 < Q1 < 0.47 and 0.44 < Q2 < 0.56, was classified as type II. When 0.1 < Q1 < 0.32 and 0.3 < Q2 < 0.44, it was classified as type III. Type I reservoirs exhibit a zigzag pattern in the northwest part of the study area. Thus, the northwest should be prioritized in actual exploration and development. Additionally, the initial productivity of tight sandstone reservoirs showed a positive correlation with the porosity, permeability, sorting coefficient, coefficient of variation, and median radius. Conversely, it demonstrated a negative correlation with the median pressure and displacement pressure. The perimeters of pores, their circularity, and the length of the major axis showed a positive correlation with the porosity, permeability, sorting coefficient, coefficient of variation, and median radius. On the other hand, they exhibited a negative correlation with the median pressure and displacement pressure. This study quantitatively constructed a new classification and evaluation system for tight sandstone reservoirs from the perspective of microscopic pore structure, achieving an overall model accuracy of 93.3%. This model effectively predicts and evaluates tight sandstone reservoirs. It provides new guidance for identifying favorable areas in the study region and other tight sandstone reservoirs.

Improved pore structure characterization and classification of strong diagenesis sandstones by data-mining analytics in Tazhong area, Tarim Basin.

The Silurian system in Tazhong area is characterized by extensive, low-abundance lithological reservoirs with strong diagenesis, resulting in significant heterogeneity. The complex pore structure in this area significantly impacts fluid control, making accurate characterization and classification of pore structures crucial for understanding reservoir properties and their influence on oil and gas distribution. Based on 314 Mercury Injection Capillary Pressure (MICP) samples in combination with core slices and thin casting slices observation, a pipeline of characterization and classification scheme by data-mining analytics of strong diagenesis sandstone pore structure types in the study zone is established, and the characteristics of different pore structures are clarified. According to the pore structure parameter abstracted by MICP data compression and variable analysis based on hierarchical clustering and principal component analysis (PCA) analysis, the variables are reasonably evaluated and screened, and the screened variables can be divided into three groups: mean pore throat radius-maximum pore throat radius-median pore throat radius-pore throat diameter mean variable group, microscopic mean coefficient variable group, and median pressure displacement pressure-relative sorting coefficient variable group. The combination of classification schemes analysed by decision tree model and linear discriminant analysis (LDA) model was determined. In the two-dimensional projection diagram of LDA model, a relatively obvious distribution of low displacement pressure, middle displacement pressure and high displacement pressure was obtained, and three distribution lines were nearly parallel. Based on the relevant information, 6 combined classification schemes suitable for final pore structure modelling were determined verified by microscopic observation. The correct characterization and classification of pore structure can be applied to the prediction of pore type, which can be used to improve the prediction of oil and gas distribution and oil and gas recovery in the future.

Impact of breathing signal-guided dose modulation on step-and-shoot 4DCT image reconstruction.

Breathing signal-guided 4DCT sequence scanning such as the intelligent 4DCT (i4DCT) approach reduces imaging artifacts compared to conventional 4DCT. By design, i4DCT captures entire breathing cycles during beam-on periods, leading to redundant projection data and increased radiation exposure to patients exhibiting prolonged exhalation phases. A recently proposed breathing-guided dose modulation (DM) algorithm promises to lower the imaging dose by temporarily reducing the CT tube current, but the impact on image reconstruction and the resulting images have not beeninvestigated. We evaluate the impact of breathing signal-guided DM on 4DCT image reconstruction and correspondingimages. This study is designed as a comparative and retrospective analysis based on 104 4DCT datasets. Each dataset underwent retrospective reconstruction twice: (a) utilizing the acquired clinical projection data for reconstruction, which yields reference image data, and (b) excluding projections acquired during potential DM phases from image reconstruction, resulting in DM-affected image data. Resulting images underwent automatic organ segmentation (lung/liver). (Dis)Similarity of reference and DM-affected images were quantified by the Dice coefficient of the entire organ masks and the organ overlaps within the DM-affected slices. Further, for lung cases, (a) and (b) were deformably registered and median magnitudes of the obtained displacement field were computed. Eventually, for 17 lung cases, gross tumor volumes (GTV) were recontoured on both (a) and (b). Target volume similarity was quantified by the Hausdorffdistance. DM resulted in a median imaging dose reduction of 15.4% (interquartile range [IQR]: 11.3%-19.9%) for the present patient cohort. Dice coefficients for lung ( ) and liver ( ) patients were consistently high for both the entire organs and the DM-affected slices (IQR lung: [entire lung/DM-affected slices only] to ; IQR liver: to ), demonstrating that DM did not cause organ distortions or alterations. Median displacements for DM-affected to reference image registration varied; however, only two out of 73 cases exhibited a median displacement larger than one isotropic 1 voxel size. The impact on GTV definition for the end-exhalation phase was also minor (median Hausdorff distance: 0.38mm, IQR: 0.15-0.46mm). This study demonstrates that breathing signal-guided DM has a minimal impact on image reconstruction and image appearance while improving patient safety by reducing doseexposure.

Poster 212: Ischial Tuberosity Avulsion Fractures: Treatment and Return to Sport in Athletes with Displaced Fragments

Objectives: Ischial tuberosity avulsion fractures are relatively rare injuries that typically occur in young athletes during activity. Some of these patients may experience significant morbidity, often through chronic pain and changes in sports participation. The influence of fragment displacement on optimal treatment and proper return to sport protocol has not been well investigated. This study sought to evaluate the relationship between displacement and both choice of treatment and time to return to sport. Methods: Retrospective analysis of ischial tuberosity avulsion fractures in pediatric patients between 2010-2021 at Boston Children’s Hospital was completed. Information regarding demographics, treatment, and recovery were extracted from individual patient charts. Plain radiographs and magnetic resonance imaging (MRI) were analyzed in order to measure fragment displacement at the ischial apophysis. Treatment protocol, return to sport (RTS) time, and complications were analyzed. Results: Eighty-eight patients with a diagnosis of an ischial tuberosity avulsion fracture were identified. Of these, 64 (73%) were treated non-operatively, 8 (9%) were treated acute operatively (within 6 weeks), and 16 (18%) were treated chronic operatively (&gt;6 weeks). Imaging for measurement of fragment displacement was available for 86 (98%) of patients. The median displacement was 0.2cm for the non-operative group, 2.2cm for the acute operative group, and 1.5 for the chronic operative group. Of the 86 patients with available imaging, 67 (78%) had a RTS time. The median RTS was 3.6 months in the non-operative group, 5.5 months in the acute operative group, and 13.3 months in the chronic operative group. Conclusions: In this retrospective cohort study, nearly all fractures with displacement &gt;= 1.0cm were surgically treated, either acutely or at a delayed time point. All patients that underwent acute operation had displacement &gt; 1.0cm, while 87% of those undergoing delayed operation had displacements &gt; 1.0cm. Those treated non-operatively returned to sport about 1 month earlier than those undergoing acute operation, and several months prior to those who underwent delayed surgical intervention. This data suggests that patients with displacement less than 1.0cm may be successfully treated through non-operative treatment and those with displacement greater than this should undergo operative treatment in the acute period to optimize outcome and return to sport.

Generating Frequency Selective Vibrations in Remote Moving Magnets

Extensive efforts in providing upper limb amputees with sensory feedback have primarily focused on the restoration of tactile capabilities, while challenges in evoking proprioceptive sensations have been poorly addressed. Previously, an human–machine interface (HMI) was proposed based on permanent magnets implanted in residual muscles of an amputee, namely the myokinetic interface, to control robotic limb prostheses. Besides control, implanted magnets offer an unprecedent opportunity to trigger musculotendon proprioceptors via untethered selective vibrations. Herein, the challenge of tracking multiple moving magnets is addressed (e.g., following muscle contractions) while being vibrated by controlled magnetic fields produced by external coils. Results demonstrate the viability of a real‐time (RT) system capable of simultaneously tracking and vibrating multiple moving magnets within a three‐dimensional workspace. Highly selective torsional vibrations in the frequency span eliciting movement illusions (70, 80, and 90 Hz) are achieved on two moving magnets, with efficiencies above 0.82 (over 80% of spectral power at the desired frequency). Tracking accuracy and precision remain robust to the coil magnetic field, with position median errors below 1.2 mm and median displacement errors below 0.95 mm. This study represents a crucial step towards the development of a bench system to study proprioception in humans.

Effect of Phase Encoding Direction on Image Quality in Single-Shot EPI Diffusion-Weighted Imaging of the Breast.

In breast diffusion-weighted imaging (DWI), distortion and physiologic artifacts affect clinical interpretation. Image quality can be optimized by addressing the effect of phase encoding (PE) direction on these artifacts. To compare distortion artifacts in breast DWI acquired with different PE directions and polarities, and to discuss their clinical implications. Prospective. Eleven healthy volunteers (median age: 47 years old; range: 22-74 years old) and a breast phantom. Single-shot echo planar DWI and three-dimensional fast gradient echo sequences at 3 T. All DWI data were acquired with left-right, right-left, posterior-anterior, and anterior-posterior PE directions. In phantom data, displacement magnitude was evaluated by comparing the location of landmarks in anatomical and DWI images. Three breast radiologists (5, 17, and 23 years of experience) assessed the presence or absence of physiologic artifacts in volunteers' DWI datasets and indicated their PE-direction preference. Analysis of variance with post-hoc tests were used to assess differences in displacement magnitude across DWI datasets and observers. A binomial test and a chi-squared test were used to evaluateif each in vivo DWI dataset had an equal probability (25%) of being preferred by radiologists. Inter-reader agreement was evaluated using Gwet's AC1 agreement coefficient. A P-value <0.05 was considered statistically significant. In the phantom study, median displacement was the significantly largest in posterior-anterior data. While the displacement in the anterior-posterior and left-right data were equivalent (P = 0.545). In the in vivo data, there were no physiological artifacts observed in any dataset, regardless of PE direction. In the reader study, there was a significant preference for the posterior-anterior datasets which were selected 94% of the time. There was good agreement between readers (0.936). This study showed the impact of PE direction on distortion artifacts in breast DWI. In healthy volunteers, the posterior-to-anterior PE direction was preferred by readers. 2 TECHNICAL EFFICACY: Stage 1.

Measuring the global mechanical properties of the human thorax: Costo-vertebral articulation

Biomechanical simulation of the human thorax, e.g. for 3D-printed rib implant optimisation, requires an accurate knowledge of the associated articulation and tissue stiffness. The present study is focusing on determining the stiffness of the costo-vertebral articulations.Specimens of rib segments including the adjacent thoracic vertebrae and ligaments were obtained from two human post-mortem bodies at four different rib levels. The rib samples were loaded with a tensile force in the local longitudinal, sagittal and transverse direction and the resulting displacement was continuously measured. The moment–angle response of the rib articulations was also determined by applying a load at the rib end in the cranial – caudal direction and measuring the resulting displacement.The torsional load response of the costo-vertebral articulations at an applied moment between −0.1 Nm and 0.1 Nm corresponded to a median range of motion of 13.2° (6.4° to 20.9°). An almost uniform stiffness was measured in all tensile loading directions. The median displacement at the defined force of 28 N was 1.41 mm in the longitudinal, 1.55 mm in the sagittal, and 1.08 mm in the transverse direction.The measured moment–angle response of the costo-vertebral articulation is in line with the data from literature. On the contrary, larger displacements in longitudinal, sagittal and transverse directions were measured compared to the values found in literature.

Assessing the impact of distortion correction on Gamma Knife radiosurgery for multiple metastasis: Volumetric and dosimetric analysis

IntroductionMagnetic resonance imaging (MRI) is a robust neuroimaging technique and is the preferred method for stereotactic radiosurgery (SRS) planning. However, MRI data always contain distortions caused by hardware and patient factors. Research questionCan these distortions potentially compromise the effectiveness and safety of SRS treatments? Material and methodsTwenty-six MR datasets with multiple metastatic brain tumors (METs) used for Gamma Knife radiosurgery (GKRS) were retrospectively evaluated. A commercially available software was used for distortion correction. Geometrical agreement between corrected and uncorrected tumor volumes was evaluated using MacDonald criteria, Euclidian distance, and Dice similarity coefficient (DSC). SRS plans were generated using uncorrected tumor volumes, which were assessed to determine their coverage of the corrected tumor volumes. ResultsThe median target volume was 0.38 cm3 (range,0.01–12.38 cm3). A maximum displacement of METs of up to 2.87 mm and a median displacement of 0.55 mm (range,0.1–2.87 mm) were noted. The median DSC between uncorrected and corrected MRI was 0.92, and the most concerning case had a DSC of 0.46. Although all plans met the optimization criterion of at least 98% of the uncorrected tumor volume (median 99.55%, range 98.1–100%) receiving at least 100% of the prescription dose, the percent of the corrected tumor volume receiving the total prescription dose was a median of 95.45% (range,23.1–99.5%). Discussion and conclusionMRI distortion, though visually subtle, has significant implications for SRS planning. Regular utilization of corrected MRI is recommended for SRS planning as distortion is sometimes enough to cause a volumetric miss of SRS targets.

Fault-displacement models for aggregate and principal displacements

New fault-displacement models (FDMs) are developed for the aggregate and principal net surface displacement using the database developed by the Fault Displacement Hazard Initiative Project. An FDM for the aggregate displacement is developed, which is then partitioned into principal and distributed displacements. The model for the aggregate displacement is first formulated in the wavenumber domain to incorporate seismology-based constraints for the extrapolation of the magnitude scaling of median displacements to large-magnitude events. The results from the wavenumber-domain model are then adjusted to fit the empirical moderate-magnitude scaling (M &lt; 7) and the shape of the displacement profile at the ends of the rupture. Segments are used in the model development to better capture the complexity of the variability of the surface-displacement profile along strike, including regions with zero displacements. For applications in which segments cannot be identified, simplified FDMs without segments are developed that treat the number, lengths, and locations of the segments as aleatory variability. The principal-displacement FDM is then developed as an adjustment to the aggregate-displacement FDM. The segmentation and the magnitude dependence of the taper length of individual segments lead to non-self-similar scaling of the median profile along the entire rupture that can have a significant impact on probabilistic fault-displacement hazard analysis (PFDHA) for sites near the ends of faults. A key feature of the new FDMs is the use of a power-normal [Formula: see text] distribution for the aleatory variability, which leads to narrower distributions of the displacement for large-magnitude earthquakes compared to the commonly used lognormal distribution. For large-magnitude earthquakes, the expected maximum displacements computed using the power-normal distribution of the FDM are consistent with the observed maximum displacements along strike, supporting the narrower shape of the upper tail of the power-normal distribution for large-magnitude events.

Predicting the need for collateral ligament repair in transolecranon fractures of the elbow: a traffic light model.

Biomechanical studies have shown that translation of the proximal radius relative to the capitellum in the sagittal plane can predict integrity of the collateral ligaments in a transolecranon fracture model; no studies have examined this in clinical practice. Nineteen consecutive transolecranon fracture dislocations were retrospectively reviewed. Data collection included patient demographics, fracture classifications, surgical management, and failure with instability. Distance between the center of the radial head and the center of the capitellum was measured on initial radiographs by 2 independent raters on 3 separate occasions. Statistical analysis was used to compare the median displacement between patients who required collateral ligament repair for stability and those who did not. Sixteen cases with a mean age of 57 years (range 32-85) were analyzed with an inter-rater Pearson coefficient of 0.89 for displacement measurement. Median displacement where collateral ligament repair was needed and performed was 17.13 mm (interquartile range [IQR]=10.43-23.88) compared with 4.63 mm (IQR=2.68-6.58) where collateral ligament repair was not performed and not required (P=.002). In 4 cases, ligament repair was not performed initially but deemed necessary based on clinical outcome and postoperative and intraoperative images. Of these, the median displacement was 15.59 mm (IQR=10.09-21.20), and 2 of these required revision fixation. Where displacement on initial radiographs exceeded 10 mm, lateral ulnar collateral ligament (LUCL) repair was required in all cases (red group). If less than 5 mm, ligament repair was not required in any case (green group). Between 5 and 10 mm, following fracture fixation, the elbow must be screened carefully to assess for any instability and a low threshold set for LUCL repair to prevent posterolateral rotatory instability (amber group). Using these findings, we propose a traffic light model to predict the need for collateral ligament repair in transolecranon fractures and dislocation.

47 Assessing the Feasibility of Cardiorespiratory Exercise During Functional MRI

Objective:To examine the feasibility of implementing a cardiorespiratory exercise stimulus during functional Magnetic Resonance Imaging (fMRI).Participants and Methods:12 young adults (age: 18-22 years) completed progressive maximal exercise testing and a brain MRI scan. During scanning, participants completed three runs of functional MRI (volumes = 619; TR = 800 ms; multiband = 4; voxel size = 3 mm3). During each 8 minute fMRI run, participants completed an exercise challenge consisting of alternating blocks of exercise and rest. Exercise was implemented with a cardiostepper, an MRI-compatible device (similar to a Stairmaster) capable of generating a cardiorespiratory exercise stimulus. During exercise blocks, participants stepped at a rate of 60 Hz with pedal resistance determined by participants' fitness level. Heart rate and respiration data were collected during MRI. fMRI data were processed and analyzed using FMRIB Software Library (FSL). The ARtifact Detection Toolbox (ART) software was also used to identify volumes with significant artifact, and ICA-AROMA was used to remove motion-related BOLD signal components.Results:During exercise blocks, heart rate increased (mean = 131 beats per minute) compared to rest (mean = 87 beats per minute; t(34) = 4.3; p &lt; .001). The mean heart rate during exercise blocks corresponds to an exercise intensity in the light to moderate intensity range for this age group. Motion (median framewise displacement) was significantly higher during exercise (mean = .53 mm) than rest (mean = .36 mm). Across all blocks, ART classified 19.8% of brain volumes as artifact-containing outliers, with 69% of the outliers occurring during exercise blocks. Although greater head motion was observed during exercise, the use of ICA-AROMA reduced the impact of motion considerably, recovering an additional 25% of the task-related signal, relative to noise. Comparison of fMRI activity during exercise versus rest revealed significant associations with primary and supplementary motor cortices, hippocampus, and the insula, among other regions.Conclusions:The current study demonstrates the feasibility of eliciting light to moderate intensity cardiorespiratory exercise (using a lower body stepping exercise) during functional MRI. Although increased head motion was observed during exercise compared to rest, the degree of head motion was roughly approximate to the values published in previous fMRI studies and post image acquisition processing improved task-related signal. During exercise, increased brain activation was observed in regions associated with the central command network, which regulates autonomic nervous system and musculoskeletal function during exercise.

Three-dimensional microanalysis of tooth movement during the first 6 months of orthodontic double retention

This study performed a 3-dimensional analysis of tooth movement during orthodontic retention to assess the effectiveness of double retention (fixed and removable) in preventing undesired tooth movement. One hundred randomly selected patients were included at the initiation of double orthodontic retention with fixed retainers and vacuum-formed splints (recommended to be worn 22 h/d) in both arches. Intraoral scans were performed directly (T0), 1 month (n= 88), 3 months (T2) (n= 78), and 6 months (T3) (n= 66) after retainer bonding. Nine reference points were marked on each tooth in every patient. Subsequent scans were superimposed, and point displacement was calculated. Statistical analysis was performed using the R statistical software (version 4.2.2; R Core Team, Vienna, Austria). Sample size calculation determined at least 55 patients were needed. The total dropout between T0 and T3 was 34 patients (did not show up for appointment). The median absolute displacement value of a single point between T0 and T3 was 0.015 mm. The most stable teeth were mandibular central incisors, whereas the least stable were mandibular molars. Most tooth displacements occurred between T0 and T2, then slowed down significantly. Double orthodontic retention prevents major tooth displacements in most patients during the first 6 months of retention; however, larger, unpredictable single-tooth displacement may occur in individual patients.

3D Surface Imaging in Reducing Setup Error for Prone Whole Breast Radiotherapy

For patients undergoing whole breast radiotherapy, treatment in the prone position allows for reduced dose to critical organs such as the heart and lungs. However, this treatment position comes with greater challenges in reproducibility and setup error given the unstable position. Our objective was to investigate the benefit of using 3D surface imaging to reduce daily setup errors for these patients. We performed a retrospective review of consecutive breast patients receiving prone breast radiotherapy at our institution. All patients were positioned initially using setup tattoos and twice a week, the positioning was adjusted using the aid of a motion tracking system. Then, a daily kilovoltage (kV) cone beam computed tomography (CBCT) image was acquired and positioning was adjusted to setup the breast and chest wall. Shifts in each translational direction were recorded and the three-dimensional vector displacement was calculated. For each patient the average displacements on days where a motion tracking system was used were compared to days whereas motion tracking system was not used. Patients were classified into significant benefit (more than 4 mm improvement), small benefit (0-4 mm improvement) or increased error (increased shifts on days a motion tracking system was used). Patient demographics were collected including stage, BMI, weight, heigh, age, ethnicity. Comparisons were made using t-tests. A total of 40 patients with stage T0-2N0 breast cancer were included. The median age was 64 and 60% of patients had left sided breast cancer. A total of 665 daily CBCT scans were analyzed, and the median daily vector displacement was 7.2 mm (1-21 mm). The median displacement on treatments where a motion tracking system was used (41% of treatments) was 6.1 mm versus 8.1 mm when not used (p<.0001). The use of a motion tracking system significantly reduced the occurrence of shifts more than 1 cm (12% vs. 33%, p < .0001) and 5 mm (65% vs. 83% p < .0001). For individual patients, 28% showed a significant improvement, 55% showed small improvement, 17% showed increased error. The median BMI was 27, weight was 71 kg, and neither was associated with an improvement in the use of Align RT (p > .05). However, patients in the small improvement group had a higher BMI than patients in the other two groups 29 vs. 25 (p = .01). A similar association was seen for weight (p < .05). No association was found for the benefit of a motion tracking system for height, age, stage or ethnicity. The use of 3D surface imaging for breast cancer patients receiving prone whole breast radiotherapy on average significantly reduced setup errors. For patients with higher BMI there was a consistent small reduction in setup error when compared to using setup marks alone. For patients with lower BMI, caution should be exercised as there was more variation with some patients demonstrating a large benefit and other patients having an increased setup error with the use of surface imaging. Further research is needed to investigate on the optimal use of this technology.

Point-of-care ultrasound for monitoring catheter tip location during umbilical vein catheterization in neonates: a prospective study.

Point-of-care ultrasound (POCUS) can guide umbilical vein catheter placement in real time and monitor catheter tip position, allowing avoidance of severe complications due to catheter malposition. This study aims to explore the effectiveness of POCUS in guiding venous catheter insertion and monitoring complications. Sixty-eight neonates with ultrasound-guided venous catheter insertion at the Neonatal Department of Dongguan Children's Hospital between December 2020 and February 2022 were included. POCUS was applied to monitor catheter tip location daily until catheter removal. A displacement range exceeding the intersection of the inferior vena cava and right atrium by ±0.5 cm was considered misalignment. Sixty-four neonates had a displaced catheter tip (94.1%, 64/68), with a median displacement distance of 0.4 cm (minimum -0.2 cm, maximum 1.2 cm). Ten neonates had a misalignment (14.7%, 10/68) caused by displacement. Displacement usually occurs within 2-4 days after placement, with displacement rates of 94.1% (64/68), 90.6% (58/64), and 98.3% (59/60) on days 2, 3, and 4, respectively, and could still occur on day 9 post-placement. In addition, misalignment mainly occurs on the second day after placement. During the monitoring process, 58 neonates had catheter tip displacement ≥2 times, resulting in 252 displacement and 22 misalignment incidents. Among them, the catheter tip migrated outward from the inferior vena cava seven times, all of which were removed in time. Ultrasound was used for positioning 486 times, and x-ray was indirectly avoided 486 times. The catheter tip is prone to displacement and misalignment after umbilical vein catheterization, which most commonly occurs on days 2-4. POCUS is recommended for daily monitoring of the tip location during umbilical vein catheterization until catheter removal.

Fixation of transverse midshaft clavicle fractures with nitinol staples vs. superior locked plating: a biomechanical study

Background: Nitinol staples have been used effectively for stabilization and compression at fracture sites. This study compared yield load, fracture displacement, and load to failure between nitinol staples and superior plating for midshaft clavicle fractures. Methods: Ten pairs of cadaveric clavicles underwent midshaft osteotomy. Each specimen in each pair was randomly assigned to fixation with superiorly placed nitinol staples or with superior plating. Specimens were loaded cyclically with increasing loads to a maximum of 1200 cycles and 60 N. Fracture displacement and construct stiffness were compared at each load. Load to failure was performed at the conclusion of testing. Results: The staple group demonstrated lower yield load and higher median fracture displacement at all levels of force compared to the plate group. Median displacement at physiologic load was 15.3 (IQR 12.8-16.5) mm for the staple construct and 2.9 (IQR 2.5-3.6) mm for plated constructs (P=2.04E-07). Median stiffness of plated constructs was significantly higher than staple constructs at all levels (P&lt;0.05). Median cycles to failure for staple constructs was significantly lower compared to plated constructs (P=0.004). Median load to failure was significantly higher for plated constructs compared to staple constructs (P=2.8E-06). Conclusions: Nitinol staple fixation of midshaft clavicle fractures demonstrated lower yield load, stiffness, increased displacement, and lower load to failure compared to superior plate fixation. However, staple constructs provided adequate stability to maintain reduction of the fracture at physiologic levels of repetitive stress, indicating a potential role for nitinol staples in clavicle fracture fixation.

Seismic Performance of RC Buildings with Different Positions of Lift Core Wall and Added Shear Walls

Nepal is situated in an area with considerable seismic activity. It is important to choose structural systems that can withstand the lateral loads. In a dual system of reinforced concrete structures, the placement of shear walls optimally increases the stiffness of the buildings. The lateral rigidity of RC buildings may be improved by strategically placing lift core walls. Buildings would be more useful if they had easy access to an elevator and stairs. Torsional irregularity in buildings would be caused by the lift core wall's eccentric location. For these kinds of structures, a bidirectional seismic excitation study is required. In design, IS 1893:2016 is applied. Drift limitations are obtained from FEMA 356 2000 for different damage conditions and median displacement values are taken as per HAZUS 4.2 SP3. This research work presents the vulnerability due to eccentric positioning of lift core in symmetrical reinforced concrete frame. The torsional irregularities are needed to be removed with optimum positioning of extra shear walls. The reduction in vulnerability of buildings due to added walls is also studied.

A ground motion model for orientation-independent inelastic spectral displacements from shallow crustal earthquakes

The peak inelastic displacement of a single-degree-of-freedom (SDOF) system is an efficient ground motion (GM) intensity measure (IM) for estimating seismic demands in structures and infrastructures. Most ground motion models (GMMs) that predict this IM are developed to estimate the arbitrary or geometric mean of the horizontal GM components obtained from the two as-recorded orientations. In this study, the median and maximum directional inelastic spectral displacements, denoted as Sdi,RotD50and Sdi,RotD100, respectively, were considered as IMs to develop GMMs. These orientation-independent measures of horizontal motion were calculated by rotating the GMs through all non-redundant rotation angles and have the advantage of removing the sensor orientation as a contributor to overall uncertainty. To do this, several SDOF systems were considered using a subset of the NGA-West2 database to fit GMMs for these IMs. A set of functional forms was developed using a mixed-effects regression approach. The predictor variables were the elastic period, T, the strength ratio, R, and a set of seismological GM causal parameters (i.e. magnitude, distance, soil condition, and so on). Comparison with existing GMMs that consider either inelastic spectral displacement or directionality is provided to highlight key differences and developments. In addition, the response directionality, defined as the ratio Sdi,RotD100/ Sdi,RotD50, was observed to be notably impacted by the strength ratio and elastic period, which has not been discussed in the literature to date. Overall, this GMM has the advantage of quantifying ground motion intensity via an efficient IM in Sdi, which can better highlight some fundamental issues surrounding the directionality of GMs and allow for more informative risk estimates.

Three-Dimensional Comparative Changes in the Pharyngeal Airway of Patients with Cleft after Two-Jaw Orthognathic Surgery.

The present study evaluated the three-dimensional changes of the pharyngeal airway after orthognathic surgery (OGS) in patients with unilateral and bilateral clefts, and in unilateral cleft patients with and without pharyngeal flap (PF). Forty-five patients with unilateral or bilateral clefts undergoing OGS were enrolled. Cone-beam computed tomographic images were obtained before and after OGS. We measured the pharyngeal airway volumes, minimal cross-sectional area, and the horizontal displacement of facial landmarks. The patients with bilateral cleft exhibited smaller initial velopharyngeal volume (unilateral, 8623 mm 3 ; bilateral, 7781 mm 3 ; P = 0.211), whereas the velopharyngeal volume increased significantly with a median of 744 mm 3 after OGS ( P = 0.031). The median horizontal displacement of A point was 2.9 and 2.6 mm among the patients with unilateral and bilateral clefts, respectively ( P = 0.276), and the median horizontal displacement of B point was -2.9 and -3.3 mm among patients with unilateral and bilateral clefts, respectively ( P = 0.618). The unilateral cleft patients with PF exhibited lower initial velopharyngeal volume (patients with a history of PF surgery, 7582 mm 3 ; patients without a history of PF surgery, 8756 mm 3 ; P = 0.129) and a lower increase in velopharyngeal volume (patients with a history of PF surgery, 437 mm 3 ; patients without a history of PF surgery, 627 mm 3 ; P = 0.739) after OGS. Midface hypoplasia and the decrease in the velopharyngeal volume were more prominent among the bilateral cleft patients and the unilateral cleft patients with PF. After OGS, the velopharyngeal volume increased considerably among the bilateral cleft patients, but no considerable differences were noted among the unilateral cleft patients with PF. Risk, II.

Spatial Fidelity of Microvascular Perforating Vessels as Perceived by Augmented Reality Virtual Projections.

Autologous breast reconstruction yields improved long-term aesthetic results but requires increased resources of practitioners and hospital systems. Innovations in radiographic imaging have been increasingly used to improve the efficiency and success of free flap harvest. Augmented reality affords the opportunity to superimpose relevant imaging on a surgeon's native field of view, potentially facilitating dissection of anatomically variable structures. To validate the spatial fidelity of augmented reality projections of deep inferior epigastric perforator flap-relevant anatomy, comparisons of three-dimensional (3D) models and their virtual renderings were performed by four independent observers. Measured discrepancies between the real and holographic models were evaluated. The 3D-printed models of deep inferior epigastric perforator flap-relevant anatomy were fabricated from computed tomographic angiography data from 19 de-identified patients. The corresponding computed tomographic angiography data were similarly formatted for the Microsoft HoloLens to generate corresponding projections. Anatomic points were initially measured on 3D models, after which the corresponding points were measured on the HoloLens projections from two separate vantage points (V1 and V2). Statistical analyses, including generalized linear modeling, were performed to characterize spatial fidelity regarding translation, rotation, and scale of holographic projections. Among all participants, the median translational displacement at corresponding points was 9.0 mm between the real-3D model and V1, 12.1 mm between the 3D model and V2, and 13.5 mm between V1 and V2. Corresponding points, including topography of perforating vessels, for the purposes of breast reconstruction can be identified within millimeters, but there remain multiple independent contributors of error, most notably the participant and location at which the projection is perceived.

Analysis of the Influence of Micro-Pore Structure on Oil Occurrence Using Nano-CT Scanning and Nuclear Magnetic Resonance Technology: An Example from Chang 8 Tight Sandstone Reservoir, Jiyuan, Ordos Basin

The micro-pore structure of a tight sandstone reservoir remarkably impacts the occurrence characteristics of the tight oil. The micro-pore structure of the Jiyuan Chang 8 tight sandstone reservoir in the Ordos Basin was examined in this research using a core physical property test, an environmental scanning electron microscope, thin section identification, and high-pressure mercury intrusion. Using nano-CT scanning and nuclear magnetic resonance technologies, representative core samples were chosen for studies evaluating the tight oil occurrence statically and dynamically. The micro-pore structure effect of a tight sandstone reservoir on the occurrence of tight oil was investigated, and the occurrence of tight oil in the reservoir forming process was discussed. It was significant to the study of tight oil in the reservoir forming process in Ordos Basin. Findings indicated that the Chang 8 reservoir in Jiyuan, Ordos Basin has poor physical properties and exhibits a high degree of heterogeneity. In addition, the oil charging simulation experiment (oil charging) can be separated into the following three stages: fast growth, gradual growth, and stability. In the process of crude oil charging, oil always preferentially entered into medium pores and large pores. These pores were the primary areas of tight oil distribution. Furthermore, the occurrence of tight oil was affected by pore type, pore structure parameters, throat parameters, and combination mode of pore and throat. First, substantially large and medium pores lead to effective pore connectivity and generate a considerable amount of tight oil. The occurrence morphology includes oil film, cluster, porous, and isolated. Second, the greater the degree of intergranular pore growth and soluble feldspar pore development, the thicker the throat, the more developed the effective throat, and the greater the quantity of tight oil. Finally, oil saturation was negatively correlated with median pressure and displacement pressure and positively correlated with sorting factors, median radius, maximum pore throat radius, and efficiency of inverted mercury.