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BACKGROUND: There is little evidence on managing the proximal aorta of 4.0-4.5 cm during aortic valve replacement (AVR) in bicuspid aortic valve (BAV) patients. METHODS: A total of 431 patients between 1993-2019 underwent either an isolated AVR, AVR + concomitant ascending aorta replacement, or aortic root replacement. We divided patients into native root dilation [4.0-4.5 cm, n=121] vs. root control groups [

The automatic brain tumor segmentation in MRI (Magnetic Resonance Images) is becoming a challenging task in the field of medicine, since the brain tumor occurs in different shapes, intensities and sizes. This paper proposes an efficient automatic brain tumor segmentation using Greedy Snake Model and Fuzzy C-Means optimization. This method initially identifies the approximate Region Of Interest (ROI), by removing the non-tumor part by two level morphological reconstruction such as dilation and erosion. A mask is formed by thresholding the reconstructed image and is eroded to improve the accuracy of segmentation in Greedy Snake algorithm. Using the mask boundary as initial contour of the snake, the greedy snake model estimates the new boundaries of tumor. These boundaries are accurate in regions where there is sharp edge and are less accurate where there are ramp edges. The inaccurate boundaries are further optimized by using Fuzzy C-Means algorithm to obtain the accurate segmentation output. The region that has large perimeter is finally chosen, to eliminate the in- accurate segmented regions. The experimental verification were done on T1-weighted contrast-enhanced image data set, using the metrics such as dice score, specificity, sensitivity and Hausdorff distance. The proposed method outperforms when compared with the traditional brain tumor segmentation methods in MRI images.

Aortic neck dilation post endovascular aneurysm repair (EVAR) has been implicated in the long-term development of endoleak and the subsequent re-intervention. Optimal endograft sizing is a vital aspect to successful repair. This study looked at percentage of graft oversizing as well as type of fixation on aortic neck dilation.We retrospectively evaluated all EVARs completed at Loyola's University from 2006 to 2015 after IRB approval. Patients without follow-up scans within a year were excluded. We collected demographics, comorbidities, graft type, size, aortic neck diameter, maximum sac size diameters from the pre-operative and follow-up scans. We reviewed and collected data on 432 patients but analyzed 154. We measured the largest aortic diameter on axial images 1 cm above and 1 cm below the lowest renal artery. Change in supra and infrarenal aortic measurements were evaluated by calculating the mm difference from each scan compared to the pre-operative scan. Linear mixed effects models were used to estimate patients' mean differences over time.We compared three groups of neck fixation grafts. Those with active suprarenal fixation had a significant change in suprarenal aortic diameter at four-year follow-up (1.86 mm, CI:0.65-3.06), compared to those with active infrarenal (0.22 mm, CI: -0.67 to -1.11) or passive suprarenal fixation (1.52 mm, CI: -0.11 to -3.15) (Fig. 1). Those with active suprarenal fixation were the only ones to have significant increase in suprarenal aortic diameter (P = 0.0026). Degree of oversizing was also divided into three groups. Oversizing by10% had less impact on the suprarenal aorta than15% oversizing at 4 years (0.41 mm, CI: -0.31 to -1.14 vs. 3.26 mm, CI: 1.63-4.88, P0.001) (Fig. 2). Oversizing had a more pronounced effect on the infrarenal aorta: 3.01 mm, CI: 2.18-3.83; 5.95 mm, CI: 3.26-8.64; and 5.05 mm, CI: 3.41-6.69 for10%, 10-15%, and15% oversizing at four years, respectively.Stent-grafts with active fixation below the renal arteries as well as oversizing by10% seem to have the least effect on aortic neck dilation over time. These factors should be considered when performing EVARs, as aortic neck dilation could lead to endoleak and need for further intervention. Further research defining the optimal stent-graft type, self-expanding versus balloon expandable, type of fixation and degree of oversizing.

Seismic fault detection is indispensable for exploring reservoirs of hydrocarbons, and a considerable amount of research has thus been devoted to it. With the rapid development of deep learning in recent years, researchers have begun using convolutional neural networks (CNNs) to identify seismic faults. However, it remains challenging for geophysical interpreters to quickly train an efficient model on a limited number of samples for fault interpretation. In this letter, we propose a workflow that uses a CNN-based method of semantic segmentation to interpret faults by using a small training set. It requires only the selection of some 2-D seismic sections from seismic volume data for interpretation and labeling to be trained to predict faults in the entire area considered. We simplified the VGG16 model to reduce training time and modified it to improve its performance. We used convolution layers instead of fully connected layers at the end of the network to implement the end-to-end classification of seismic images, and adopted dilation convolution to increase the receptive field and hybrid dilation convolution to avoid problems in it. We also applied the atrous spatial pyramid pooling (ASPP) module to further enhance the effects of segmentation. The results were subjected to postprocessing for refinement. The promising performance of the proposed method was verified on a set of real seismic data.

The aim of this study was to evaluate the role of wall shear stress (WSS) as a predictor of ascending aorta (AAo) growth at 5 years or greater follow-up.Aortic 4-dimensional flow cardiac magnetic resonance (CMR) can quantify regions exposed to high WSS, a known stimulus for arterial wall dysfunction. However, its association with longitudinal changes in aortic dilation in patients with bicuspid aortic valve (BAV) is unknown.This retrospective study identified 72 patients with BAV (age 45 ± 12 years) who underwent CMR for surveillance of aortic dilation at baseline and ≥5 years of follow-up. Four-dimensional flow CMR analysis included the calculation of WSS heat maps to compare regional WSS in individual patients with population averages of healthy age- and sex-matched subjects (database of 136 controls). The relative areas of the AAo and aorta (in %) exposed to elevated WSS (outside the 95% CI of healthy population averages) were quantified.At a median follow-up duration of 6.0 years, the mean AAo growth rate was 0.24 ± 0.20 mm/y. The fraction of the AAo exposed to elevated WSS at baseline was increased for patients with higher growth rates (0.24 mm/y, n = 32) compared with those with growth rates 0.24 mm/y (19.9% [IQR: 10.2%-25.5%] vs 5.7% [IQR: 1.5%-21.3%]; P = 0.008). Larger areas of elevated WSS in the AAo and entire aorta were associated with higher rates of AAo dilation0.24 mm/y (odds ratio: 1.51; 95% CI: 1.05-2.17; P = 0.026 and odds ratio: 1.70; 95% CI: 1.01-3.15; P = 0.046, respectively).The area of elevated AAo WSS as assessed by 4-dimensional flow CMR identified BAV patients with higher rates of aortic dilation and thus might determine which patients require closer follow-up.

A bearing capacity evaluation for the surface strip foundation on a working platform modelled on a two-layered substrate is considered in the study. The upper layer is assumed as man-made and well-controlled and thus non-variable. The lower layer modelling natural cohesive soil is subjected to spatial variability of undrained shear strength. The random failure mechanism method (RFMM) is used to evaluate the bearing capacity. This approach employs a kinematic assessment of the critical load and incorporates the averaging of three-dimensional (3D) random field along dissipation surfaces that result from the failure geometry. A novel version of the approach considering an additional linear trend of undrained shear strength in the spatially variable layer is proposed. The high efficiency of the RFMM algorithm is preserved. The influences of foundation length, trend slope in the spatially variable layer, fluctuation scales, and thickness of the homogenous sand layer on the resulting bearing capacity evaluations are analysed. Moreover, for selected cases, verification of the RFMM based assessment obtained using random finite difference method (RFDM) based on 3D analysis is provided. Two types of analyses are performed using RFDM based on associated and non-associated flow rules. For associated flow rule which corresponds to RFDM, the RFMM is conservative and efficient and thus it seems preferable. However, if RFDM employs non-associated flow rule (much lower dilation angle for sand layer), the efficient RFMM is no longer conservative. For this situation, a combined approach that improves the efficiency of the numerical method is suggested.

PetroChina’s Karamay heavy oil reservoirs mostly comprise Jurassic deposits of braided fluvial facies that have a low porosity, extremely high bitumen viscosity, and strong heterogeneities within the reservoir. Steam-assisted gravity drainage (SAGD) dilation start-up has been proven to be an efficient reservoir geomechanical stimulation method as it shortens the steam circulation time, reduces steam usage, and increases the oil production rates. This method worked well on relatively good-quality oil sand reservoirs. However, for reservoirs with heterogeneous reservoir properties along the SAGD well, field well production data indicated the presence of non-uniform steam chambers in post-dilation SAGD wells. Enhanced dilation methods, such as vertical well assisted SAGD dilation (VW-SAGD-Dilation) are have been used, and field pilot tests have yielded promising results. This reservoir stimulation process utilizes one or more vertical wells beside the SAGD well to initiate the formation of dilation zones that connect to the dilation zone formed during the conventional SAGD dilation start-up. Compared with the normal SAGD dilation start-up, this composite dilation process creates a uniform dilation zone along the SAGD well, thus improving the thermal conformance and well productivity. The vertical well and SAGD well are connected by this composite dilation zone, which enables the combined use of the SAGD process and cyclic steam stimulation process. This paper presents our understanding and numerical case studies of this enhanced dilation strategy. The well production data from the post-dilation wells were positive (uniform steam chamber growth and higher oil rate), which highlights the promising potential of using geomechanical dilation as a reservoir stimulation method to create a large stimulated reservoir volume in heterogeneous super-heavy oil reservoirs.

Concrete-filled fiber-reinforced polymer (FRP) tubes (CFFTs) are attractive as beams and arches in harsh environments due to their durability and ease of erection. A successful infrastructure application is the use of multiple, buried CFFT arches in short-span bridges. To effectively analyze and design CFFT arches under complex loadings, there is a need for numerical procedures that capture the structural behavior of CFFT arches including the effects of FRP confinement on the concrete core and second-order response. Here, a computationally efficient structural finite-element analysis technique for the second-order inelastic behavior of these CFFT arches is detailed. A curved, flexibility-based, layered-frame element is employed to handle geometric and material nonlinearities. A concrete constitutive model that explicitly considers the effect of dilation of the concrete core and confinement provided by the FRP tube is implemented. A bending test was performed on a CFFT arch, and experimental data compared with model predictions. Additional comparisons are made with CFFT arch and beam bending tests available in the literature. The model is shown to accurately predict the load-carrying capacity and ductility of CFFT members, and to capture arch collapse mechanisms arising from FRP rupture and concrete crushing.

INTRODUCTION Hiatal hernia recurrence following surgical repair is common. We sought to define the most common anatomic location and mechanism for hiatal failure to inform technical strategies to decrease recurrence rates. METHODS Retrospective chart review and video analysis were performed for all recurrent hiatal hernia operations performed by a single surgeon between January 2013 and April 2020. Hiatal recurrences were defined by anatomic quadrants. Recurrences on both left and right on either the anterior or posterior portion of the hiatus were simply classified as 'anterior' or 'posterior', respectively. Three or more quadrants were defined as circumferential. Mechanism of recurrence was defined as disruption of the previous repair or dilation of the hiatus. RESULTS There were 130 patients to meet criteria. Median time to reoperation from previous hiatal repair was 60 months (IQR19.5-132). First-time recurrent repairs accounted for 74%, second time 18%, and three or more previous repairs for 8% of analyzed procedures. Mesh had been placed at the hiatus in a previous operation in 16%. All reoperative cases were completed laparoscopically. Video analysis revealed anterior recurrences were most common (67%), followed by circumferential (29%). There were two with left-anterior recurrence (1.5%), two posterior recurrence (1.5%), and one right-sided recurrence. The mechanism of recurrence was dilation in 74% and disruption in 26%. Disruption as a mechanism was most common in circumferential hiatal failures. Neither the prior number of hiatal surgeries nor the presence of mesh at the time of reoperation correlated with anatomic recurrence location or mechanism. Reoperations in patients with hiatal disruption occurred after a shorter interval when compared to hiatal dilation. CONCLUSION The most common location and mechanism for hiatal hernia recurrence is anterior dilation of the hiatus. Outcomes following techniques designed to reinforce the anterior hiatus and perhaps to prevent hiatal dilation should be explored.

BACKGROUND Balloon dilation of the eustachian tube is a new therapeutic option for eustachian tube dysfunction. One of the limiting factors of wider adoption of this technique in many parts of the world is the high cost of the devices, in spite of regulatory approval of safety. OBJECTIVE Evaluate the performance and usability of standard less-expensive endovascular balloons for eustachian tube dilation in comparison to an approved device in a preclinical study. STUDY DESIGN Comparative cadaver feasibility study. SETTING University tertiary care facility. METHODS Ten eustachian tube dilations were performed with an approved eustachian tube dilation device. Ten other procedures were carried out with an endovascular balloon of similar dimensions. Cone beam computerized tomography was performed to evaluate the extent of dilation and possible damages. The lumen and mucosal lining were inspected endoscopically post-dilation. Volume measurements were compared before and after the procedure in both groups using contrast enhancement. RESULTS All 20 eustachian tube dilations were carried out successfully. No tissue damages could be identified on cone-beam computerized tomography or via endoscopic examination. There was a statistically significant difference of eustachian tube volumes between pre- and post-dilations, with no statistically significant difference between the devices. CONCLUSION Eustachian tube dilation with a less costly endovascular balloon achieved similar results to an approved eustachian tube dilation device. No damages or any other safety concerns were identified in a cadaver study.

Summary Although atrial dilation is a common finding in feline cardiac disease, detailed investigations of atrial pathology are rare in cats. The aim of the study was to investigate the correlation between pathohistological findings, morphometric data and the degree of dilation of the left atrial appendage (LAA) in 53 cats. Based on the LAA volume, the samples were grouped into normal/control (group 0, ≤1 ml [n = 9]), mildly dilated (group 1, >1 to ≤2 ml [n = 16]), moderately dilated (group 2, >2 to ≤3 ml [n = 14]) and markedly dilated (group 3, >3 ml [n = 14]) groups, independent of the underlying disease. Samples from the LAA and the left atrium (LA) were histologically evaluated using haematoxylin and eosin- and Picrosirius red-stained sections, and morphometrically analysed using an image analysis system. The degree of endo-, myo- and epicardial fibrosis was directly correlated with increased LAA dilation. Due to cardiomyocyte hyperplasia and hypertrophy, the mean thickness of the atrial wall was significantly greater in groups 1 and 2 than in group 0. Conversely, group 3 had a lower mean atrial wall thickness than groups 1 and 2, which was attributed to increased transmural fibrosis and cardiomyocyte atrophy. These findings reflect intensive dynamic remodelling processes during LA and LAA dilation, indicating that reversibility appears to be limited in cases of severe left atrial dilation.

The micro-texture of the aggregates of a pavement layer has a direct influence on their resistance. Whatever the position of these aggregates in a pavement structure, they must withstand, during construction or during life, the stresses of attrition and impact. In this study, a series of mechanical tests (Proctor, Los-Angeles and Micro-Deval) are carried out on grains of local materials (limestone and shale), the degree of crushing of the grains has been quantified using the concept of fractal dimension. The fractal dimension was calculated for the different grains constituting the samples before and after each test, with the use of two two-dimensional 2D methods (Masses Method at the scale of a sample and the Box Counting Method at the scale of a grain) and a three-dimensional 3D method (Blanket on a grain scale) which is based on the use of the difference between erosion and dilation. We seek to determine from these methods the correlation between the two fractal dimensions, namely 2D and 3D and study the influence of different parameters on the mechanical characteristics of the materials chosen: the shape and size of the grains, the presence or absence of water, the stress intensity as well as the nature of the material. The results obtained show that the three-dimensional method has a positive effect on the description of the 3D microstructure of the surface of the grains subjected to the various mechanical tests.

Modified Lade criterion can not only describe the strength properties of many kinds of rocks well but also has simple and practical parameters. Although the elastoplastic solution of circular tunnel has been extensively investigated, the method based on modified Lade criterion considering the effect of the intermediate principal stress, strain-softening behavior, and dilatancy has not yet been studied. In this paper, a new numerical procedure based on modified Lade criterion is proposed to calculate the elastoplastic solutions for surrounding rock of the circular tunnel. The comparisons of stress, displacement, and plastic zone radius are carried out between the presented method and published literatures under axisymmetric and nonaxisymmetric original in situ stress field. Finally, a series of parametric analyses are executed and discussed. It can be concluded that the lateral pressure coefficient, λ, influences both the size of plastic zone and the development direction. The plastic zone radius shows a negative power function change with increasing critical deviatoric plastic strain and increases slightly with increasing dilation angle, ψ.

OBJECTIVES To evaluate the ability of photocurable gelatin to prevent stricture recurrence after urethral dilation in a rabbit urethral stricture model. METHODS We created urethral strictures in the bulbar urethras of 10 male Japanese white rabbits using electrocoagulation. After 1 month, the rabbits were randomly divided into Group A (n = 5; urethral stricture dilation and the local application of photocurable gelatin using a ruthenium photoinitiator and irradiation with a light-emitting diode light [λ = 455 nm, 50 mW/cm2 ] for 1 min) and Group B (n = 5; dilation only). Urethral stricture status was evaluated 1-2 months later by retrograde urethrography and urethroscopy. The lumen ratio (urethral width at the stricture site to the normal urethral width on retrograde urethrography) was calculated. Urethral patency was considered to be improved when the urethral lumen could accommodate a 10-Fr urethroscope without resistance. Urethral specimens were harvested for histopathological examination. RESULTS The mean lumen ratio did not differ significantly between Groups A and B before dilation (25.8% vs 23.4%; P = 0.40), but differed significantly after dilation (65.5% vs 27.3%, respectively; P = 0.03). Urethral patency improved in all rabbits in Group A (100%) versus one rabbit in Group B (20%; P = 0.02). The mean circumference of the regenerated urethral epithelium at the stricture site was larger in Group A than in Group B (14 mm vs 6.6 mm; P = 0.06). CONCLUSIONS Photocurable gelatin can reduce urethral stricture recurrence after dilation in a rabbit model.

The proximal optimizing technique (POT) -proximal balloon edge dilation (PBED) sequence for side branch (SB) dilatation with cross-over single-stent implantation decreases both strut obstruction at the SB ostium and stent deformation at the main branch (MB).The purpose of this experimental bench test was to assess the impact of stent design on stent deformation, obstruction by stent struts at a jailed SB ostium, and stent strut malapposition in the POT-PBED sequence.Fractal coronary bifurcation bench models (60- and 80-degree angles) were used, and crossover single-stent implantation (3-link stent: XIENCE Sierra, Abbott Vascular, Santa Clara, CA, n = 10; 2-link stent: Synergy, Boston Scientific, Marlborough, MA, n = 10) was performed from the MB using the POT-PBED sequence. Jailing rates at the SB ostium, stent deformation, and stent strut malapposition of the bifurcation segment were assessed using videoscopy and optical coherence tomography.After SB dilatation using the PBED technique, jailing rates at the SB ostium and stent deformation did not differ significantly between the two types of stents. Conversely, the rate of malapposed struts of the bifurcation segment after the PBED procedure was significantly lower with 3-link stents than with 2-link stents for both 60- and 80-degree angles (60-degree angle: 4.3% ± 4.4% versus 22.0% ± 11.1%, P = 0.044; 80-degree angle: 20.8% ± 15.1% versus 57.2% ± 17.0%, P < 0.001, respectively).In the POT-PBED sequence, 3-link stents might be a preferable coronary bifurcation stent, maintaining a jailed SB ostium while significantly reducing stent strut malapposition of the bifurcation segment when compared with 2-link stents.

With over 172 Million people infected with the novel coronavirus (COVID-19) globally and with the numbers increasing exponentially, the dire need of a fast diagnostic system keeps on surging. With shortage of kits, and deadly underlying disease due to its vastly mutating and contagious properties, the tired physicians need a fast diagnostic method to cater the requirements of the soaring number of infected patients. Laboratory testing has turned out to be an arduous, cost-ineffective and requiring a well-equipped laboratory for analysis. This paper proposes a convolutional neural network (CNN) based model for analysis/detection of COVID-19, dubbed as CovCNN, which uses the patient's chest X-ray images for the diagnosis of COVID-19 with an aim to assist the medical practitioners to expedite the diagnostic process amongst high workload conditions. In the proposed CovCNN model, a novel deep-CNN based architecture has been incorporated with multiple folds of CNN. These models utilize depth wise convolution with varying dilation rates for efficiently extracting diversified features from chest X-rays. 657 chest X-rays of which 219 were X-ray images of patients infected from COVID-19 and the remaining were the images of non-COVID-19 (i.e. normal or COVID-19 negative) patients. Further, performance evaluation on the dataset using different pre-trained models has been analyzed based on the loss and accuracy curve. The experimental results show that the highest classification accuracy (98.4%) is achieved using the proposed CovCNN model.

The constant normal stiffness (CNS) boundary condition is more representative for the underground engineering, in which the shear-induced dilation is restricted by surrounding rocks, resulting in an increase in the normal stress. Therefore, the use of CNS boundary conditions in the research of shear-slip failure of underground rock engineering is more in line with the actual situation. Taking the instability and failure of surrounding rock in underground engineering as the background, the present study introduces the engineering background of CNS boundary conditions and the research progress on shear characteristics of rock joints under CNS boundary conditions. Three key directions for future research are proposed based on the latest research results of shear characteristics of rock joint under CNS boundary conditions: ① developing a rock joint shear test system that can realize the function of “CNS boundary conditions + shear-seepage test + visualization”; ② carrying out the shear tests of real rock joints under CNS boundary conditions based on 3D scanning and 3D carving technology; and ③ carrying out the shear tests of rock joint network under CNS boundary conditions.

The changes in the contribution of ATP-sensitive potassium channels (KATP) to basal vascular tone maintenance and acetylcholine (ACh)-mediated dilation of pial arteries after global cerebral ischemia (2VO + hypo model) caused by a single cerebral ischemia–reperfusion were studied in Wistar rats. Ischemia was modeled by bilateral carotid artery clamping for 12 min paralleled by maintaining the mean arterial pressure at 45 ± 2 mm Hg. Sham-operated rats served as a control. Vascular examination was performed on days 7, 14 and 21 after ischemia. Changes in the contribution of KATP channels to the basal vascular tone were assessed using intravital microphotography by the number of vessels constricted in response to the effect of a KATP channel blocker glibenclamide (10 µM). Changes in the contribution of KATP channels to vascular dilation were assessed by comparing the number and degree of arterial dilation in response to ACh (10–7 M, 5 min) before and after glibenclamide application. It was found that ischemia reduces the role of KATP channels in basal vascular tone maintenance in pial arteries during 14 days after ischemic exposure. At the same time, the role of KATP channels in the implementation of ACh-mediated dilatory responses of pial arteries also decreases. By postischemic day 21, KATP channels are virtually no longer involved in the dilatory response to ACh.

Background: Induction of labour is poorly understood even though it is performed in 20% of births in the United States. One method of induction, the balloon dilator applied with traction to the interior os of the cervix, engages a softening process, permitting dilation and effacement to proceed until the beginning of active labour. The purpose of this work is to develop a simple model capable of reproducing the dilation and effacement effect in the presence of a balloon. Methods: The cervix, anchored by the uterus and the endopelvic fascia was modelled in pre-labour. The spring-loaded, double sliding-joint, double pin-joint mechanism model was developed with a Modelica-compatible system, MapleSoft MapleSim 6.1, with a stiff Rosenbrock solver and 1E-4 absolute and relative tolerances. Total simulation time for pre-labour was seven hours and simulations ended at 4.50 cm dilation diameter and 2.25 cm effacement. Results: Three spring configurations were tested: one pin joint, one sliding joint and combined pin-joint-sliding-joint. Feedback, based on dilation speed modulated the spring values, permitting controlled dilation. Dilation diameter speed was maintained at 0.692 cm · hr−1 over the majority of the simulation time. In the sliding-joint-only mode the maximum spring constant value was 23800 N · m−1. In pin-joint-only the maximum spring constant value was 0.41 N·m· rad−1.With a sliding-joint-pin-joint pair the maximum spring constants are 2000 N · m−1 and 0.41 N · m · rad−1, respectively. Conclusions: The model, a simplified one-quarter version of the cervix, is capable of maintaining near-constant dilation rates, similar to published clinical observations for pre-labour. Lowest spring constant values are achieved when two springs are used, but nearly identical tracking of dilation speed can be achieved with only a pin joint spring. Initial and final values for effacement and dilation also match published clinical observations. These results provide a framework for development of electro-mechanical phantoms for induction training, as well as dilator testing and development.

The detectability of fibrils in mammographic phantom images by morphological enhancement was analysed in the present study. Materials that mimic fibrils were imaged by a digital mammography machine at 28 and 29 kVP. The images were processed by a dilation technique to produce second set of images. Receiver operating characteristic analysis was performed to compare the detection performance from the two sets of images. As compared to original images, the 28 kVP’s fibrils images from dilation technique become more prominence to be detected by observers. While at 29 kVP only a few observers can found the fibrils images from dilation technique. This study suggests morphological enhancement of mammography image did not increase the detection of low frequency signals of the images.

Torque as a tightening method is a simple technique that can be used to tighten a bolt to a given pre-load. Therefore, it is important to theoretically derive an accurate torque vs tension relationship for threaded fasteners as this would enable the industry to achieve a reliable pre-load. Various attempts were made to develop a complete theoretical relationship between torque and tension. Due to the thread angle there exists a nut dilation force causing the nut to expand radially out wards. This effect is more prominent in nuts with smaller height (Style 0 hex nut, refer ISO 4035 1 ). This nut dilation force creates a combined frictional effect with the drive torque thus affecting the torque tension relationship. This paper proposes a novel 3D formulation for torque tension relationship taking into consideration the nut dilation effect. This paper further develops new formulae for tightening and loosening torque, retaining torque, tension vs nut rotational angle relationship as well as formula for nut dilation force for both tightening and loosening.

Gauging the mechanical effect of partial saturation in granular materials is experimentally challenging due to the very low suctions resulting from large pores. To this end, a uniaxial (zero radial stress) compression test may be preferable to a triaxial one where confining pressure and membrane effects may erase the contribution of this small suction; however, volume changes are challenging to measure. This work resolves this limitation by using X-ray imaging during in situ uniaxial compression tests on Hamburg Sand and glass beads at three different initial water contents, allowing a suction-dependent dilation to be brought to the light. The acquired tomography volumes also allow the development of air–water and solid–water interfacial areas, water clusters and local strain fields to be measured at the grain scale. These measurements are used to characterise pertinent micro-scale quantities during shearing and to relate them to the measured macroscopic response. The new and well-controlled data acquired during this experimental campaign are hopefully a useful contribution to the modelling efforts—to this end they are shared with the community.

Background More than a decade after its introduction, some rhinologic surgeons have incorporated the technique of balloon sinus dilation (BSD) technology into “hybrid” endoscopic sinus surgery (ESS) procedures. A novel BSD device which can be placed over standard surgical instruments, including surgical navigation instruments, has recently been introduced. We present a case series in which this device was used as a hydraulic dissection tool to aid safe efficient surgery in difficult‐to‐access locations of the paranasal sinuses during hybrid ESS procedures. Objective Highlight the potential role of hydraulic dissection techniques during ESS utilizing BSD. Methods Retrospective case series of patients who underwent ESS performed in part with a novel BSD device. Results A total of 10 patients who underwent hybrid ESS with BSD were reviewed. In all 10 cases, the novel BSD device was used without complication. The device was used over straight and curved suctions while being tracked with surgical navigation in all cases. Thirteen posterior ethmoid dissections, 12 sphenoidotomies, and 8 frontal sinusotomies were assisted with the device. For the selected dissections in which the balloon was utilized, the operating surgeon found it to be helpful in creating more space in difficult to access areas which allowed for continued safe surgical dissection. Conclusions Sinus balloon devices can be used as a hydraulic dissection tool and may be a useful adjunct during ESS. The novel dilation system used in this study, which deploys a sinus balloon device over standard surgical instruments with surgical navigation, provides even more opportunity to accurately dissect difficult areas of the paranasal sinuses safely and efficiently. Further studies evaluating the exact role of sinus balloon devices used as a hydraulic dissection tool during ESS are warranted. Level of Evidence 4., Sinus balloon devices can be used as a hydraulic dissection tool and may be a useful adjunct during endoscopic sinus surgery. A novel dilation system, which deploys a sinus balloon device over standard surgical instruments with navigation, provides even more opportunity to accurately dissect difficult areas of the paranasal sinuses safely and efficiently.

Purpose: Migration is a major cause of reintervention after endovascular aneurysm repair (EVAR). In patients with common iliac artery (CIA) dilation due to proximal migration of the iliac limb, internal iliac blood flow can be preserved by implanting an iliac branch device (IBD). Case Report: In this report, we discuss the case of a patient in whom the bilateral limbs were completely displaced into the aortic aneurysm due to proximal migration of the iliac limb after EVAR. By taking advantage of the characteristics of this migration, we formed a pull-through wire through the native terminal aorta without passing through the flow divider of the stent graft, and the IBD was deployed safely. Conclusion: The present case indicates that the preservation of at least 1 internal iliac artery is possible in patients with CIA dilation due to proximal migration of the iliac limb. However, the unique features of each case must be considered to determine the appropriate approach.

Gamma-ray bursts (GRBs) come in two types, short and long. The distribution of logarithmic durations of long GRBs is asymmetric rather than Gaussian. Such an asymmetry, when modelled with a mixture of Gaussian distributions, requires an introduction of an additional component, often associated with another class of GRBs. However, when modelled with inherently asymmetric distributions, there is no need for such a component. The cosmological dilation was already ruled out as a source of the asymmetry, hence its origin resides in the progenitors. GRB light curves (LCs) are usually well described by a series of fast-rise-exponential-decay pulses. A statistical analysis of ensembles of simulated LCs shows that the asymmetry is a natural consequence of the pulse shape and the multi-pulse character of the LCs., Comment: 8 pages, 3+2 figures; accepted in MNRAS

A new concept called the transmission ratio of ground volume loss (TRGVL) is proposed to describe the variation law of ground volume loss with depth above the tunnel. Based on the developed Gaussian function, the formula for TRGVL is deduced. Further, the first-order derivative of TRGVL is presented to evaluate the dilation and compression degree of the soil at any depth above the tunnel. A total of 15 cases, involving eight field project cases and seven model test cases, are investigated to validate rationality of the proposed formula. The results of field projects and model test cases indicate variation in TRGVL presents four forms. By analysing the volumetric deformation of the soil above the tunnel, formation mechanism of the each form of TRGVL is revealed. Finally, the evolution of the four forms of TRGVL is used to evaluate the disturbance degree of the soil above the tunnel.

A novel microcrack damage theory for describing the time-dependent behavior of brittle rocks is proposed. Instead of using scalar or tensorial variables to approximate the effect of microcracks, the concept of directional damage is introduced by upscaling the directional distribution density of microcracks through the noninteracting homogenization scheme. The contribution of an individual crack on global strain is first derived from the crack-opening displacements including sliding, closure, and dilation. The model is then cast in the free energy form, and the range of parameters ensuring compliance with the second law of thermodynamics is derived rigorously. Considering that the subcritical propagation of microcracks is the dominant mechanism behind the time-dependent deformation and failure of brittle rocks, the driving force for directional damage is defined as the corresponding energy release rate, and the effect of time is introduced through a damage evolution law inspired from the kinetics of subcritical crack growth. The model is applied to simulate the behavior of basalt rock under various loading conditions. In addition to predicting the stress–strain–time response, the model offers enhanced resolution in representing the anisotropic characteristics of microcrack-induced damage in brittle rocks and their time-dependent evolutions.

Triaxial compression tests are conducted for the micritized framework reef limestone, which is sampled from a reef island in the South China Sea. The lateral strain response method (LSR) is applied to figure out the crack initiation stress of the reef limestone sample under different confining pressures. With a low porosity and a high dry density, the micritized framework reef limestone has higher compressive strength compared to the rudstone and bioclastic limestone from shallow reef associated strata. Under a confining pressure of 0–8 MPa, the crack initiation stress of the specimen is estimated to be 52%–69% of the peak compressive strength. The crack initiation stress increases when the confining pressure increases. Under different confining pressures, the lateral strain of the specimen when it fails is smaller than terrigenous rocks all the time. Further analysis shows that the lateral strains of the specimen when crack initiation occurs under different confining pressures are similar (with a value of

The artificial ground freezing (AGF) method has been widely used in underground engineering construction. As the main load-bearing elements of the AGF method, the strength of frozen walls is expected to play a crucial role in engineering stability. To improve the accuracy of quantitative evaluations of engineering stability, it is necessary to grasp the strength characteristics of frozen rock during service. To achieve this, the red sandstone taken from a frozen shaft project was tested via triaxial compression at different temperatures (−5°C,−10°C,−15°C,−20°C,−25°C, and −30°C). After that, a damage constitutive model with a Weibull distribution was derived to characterize the damage development of the frozen sandstone. Based on the validated model, the variation of damage degree was analyzed. The results show that the crack initiation stress, crack dilation stress, and peak strength all increase with decreasing temperature. The crack damage threshold increases as the frozen sandstone strength increases. The presented damage constitutive model can reflect the damage evolution of frozen sandstone. When the stress exceeds the crack initiation stress, the damage degree begins to increase, and it increases quickly when the stress approaches the peak strength. The model parameters can reflect the influence of negative temperatures on the strength of frozen sandstone. The crack damage threshold could be treated as an essential intrinsic property for predicting the failure process of frozen sandstones. The results can provide an important reference for the design and construction of frozen ground engineering.

The present study aimed to simulate the interaction between hydraulic fractures and natural fractures using hydromechanical coupling in the bonded particle model using the smooth joint method, followed by sensitivity analysis regarding the angle of approach of the pre-existing fractures relative to the direction of the hydraulic fracture, strength of the natural fractures, and ratio of the in-situ stresses. In the present research, the model of hydraulic fracture in a reservoir with natural fractures was assessed by hydromechanical coupling, implemented in the discrete element method, based on the BPM. Considering the discontinuous nature of the current research, the BPM-based PFC2D software was applied to simulate the interaction of hydraulic fractures and natural fractures. At first, the microparameters that correspond to the macroscale characteristics of the rock were identified by comparison with experimental results through repetitive calibration. DEM results were compared with experimental results from uniaxial compressive and Brazilian test scale model testing. Sensitivity analysis was performed in terms of the angle of approach parameters of natural fractures, joint strength, and in-situ stress ratio. According to the results of the modeling processes, the shape of the time history curves of wellbore pressure was the same for various angles of approach of 30, 60, and 90 degree relative to the vertical direction. Since the hydraulic fracture tended to be grown and propagated in the direction of the least strength, it propagates in the pre-existing fractures without strength or their dilation. The hydraulic fracture breakdown largely depended on the ratio of the in-situ stresses as in a similar state of the maximum principal stress, the value of the minimum principal stress had considerable effects on the fracture propagation pattern. The breakdown pressures of the hydraulic fracture with the increased heterogeneity and ratio of the in-situ stresses decreased in a similar situation of the value of the maximum principal stress. The modeling results indicated that the hydraulic pressure and onset of breakdown time largely depended on the value of the minimum principal stress, so that the increased minimum principal stress would increase the hydraulic fracture and onset time of fracturing. The hydraulic fracture pattern depended on in-situ stresses, and the higher in-situ stress ratios were associated with the increased length of the fracture experiencing aperture.

En-echelon fractures widely exist in natural rock masses. Although the formation and occurrence features of en-echelon fractures have been extensively studied by geologists, the anisotropic mechanical behavior caused by en-echelon fractures has received little attention. In this study, a set of idealized en-echelon fractures were prefabricated and subjected to direct shear tests. The influence of structural parameters (e.g., fracture angle and persistency) of en-echelon fractures on shear strength, friction and dilation behavior, shear failure structures, and acoustic emission response was comprehensively evaluated. The test results show that the shear of en-echelon fractures involves a cracking stage and a shear-slipping stage. These two stages can be quantitatively described by three shear strength indices and three dilation indices, which present varying degrees of anisotropy under different shear stages and boundary conditions. Also, various types of failure structures evolved from en-echelon fractures can be observed. They essentially depend on different crack types and coalescence patterns of rock bridges and greatly affect the friction and dilation characteristics in the shear-slipping stage. Based on the test results, the anisotropic micro-cracking mechanism was first discussed, and then an idealized vertical slope analysis was performed. Finally, some implications were discussed for the fault structures in field and the deep fault behavior.

MitraClip implantation has become the standard transcatheter mitral valve repair (TMVR) technique for severe mitral regurgitation (MR). However, approximately one third of patients have poor outcomes, with MR recurrence at follow-up. The aim of this study was to investigate whether quantitative analysis of mitral valve (MV) geometry on three-dimensional (3D) echocardiography can identify geometric parameters associated with the recurrence of severe functional MR (FMR) versus organic MR (OMR) at 6-month follow-up after TMVR using the MitraClip.Sixty-one patients with severe FMR (n = 45) or OMR (n = 16) who underwent transesophageal 3D echocardiography before and 6 months after TMVR were retrospectively analyzed. MV geometry was quantified using 3D echocardiography software. Vena contracta area (VCA) at 6-month follow-up was used to define two outcome groups: patients with good results with VCA 0.6 cmMR recurrence was found in 34% of all study patients (21 of 61). In patients with FMR, significant differences between MR 0.6 and MR ≥ 0.6 were found at baseline for tenting index (1.13 vs 1.23, P = .004), tenting volume (2.8 vs 4.0 ml, P = .04), indexed left ventricular (LV) end-diastolic volume (68.0 vs 99.9 ml/mMR recurrence after TMVR in patients with FMR is associated with advanced LV dilation and MV tenting before TMVR, which provides clinical implications for a point of no return beyond which progressive LV dilation with MV geometry dilation and tethering cannot be effectively prevented by TMVR. In contrast, no significant determinants of MR recurrence and progressive MV annular dilation could be identified in patients with OMR.

Cardiac catheterization is an invasive diagnostic procedure for treating the cardiovascular diseases. This paper aims to understand the transport phenomena of blood nanofluid through a flexible arterial domain, which has stenosis/dilation with the catheter outer surface layered with nanoparticles. Blood is considered as a micro-polar fluid, governed by nonlinear equations, which are then solved by using the homotopy perturbation method. We consider the flexible nature of the arterial wall as a function of time due to the heart’s pumping action. Different slip velocities with the Darcy effects in the constricted domain’s abnormal segments represent the dysfunction of a blood vessel. In this paper, we explore the effects of the various fluid parameters and the embedded geometrical parameters on physiological characteristics. We observe that the radial velocity increases with the increasing value of Gr and Br. However, impedance has shown the opposite pattern in the dilation segment. Also, we understand the helical flow distribution in the abnormal segments of the considered blood vessel. These findings explain that the study of nanofluid could be an assuring therapeutic approach against arterial conditions.

Los aneurismas aórticos corresponden a una dilatación focal de la pared de la arteria que supera el 50% de su diámetro normal. La mayoría de los casos corresponden a la localización abdominal, siendo una pequeña proporción descritos a nivel de la aorta torácica. En este segmento, menos del 10% de los pacientes experimentan síntomas e incluso, la ruptura puede constituir la primera manifestación. Se presenta el caso de una mujer octogenaria con hemoptisis e inestabilidad hemodinámica en la que se realizó el diagnóstico de aneurisma de aorta torácica a través angiotomografía contrastada para luego recibir manejo endovascular de manera exitosa. Dado el pronóstico de esta patología, es vital un adecuado uso de los estudios de imagen para un acertado diagnóstico radiológico que permita un enfoque terapéutico oportuno.

In this work, a novel constitutive model is developed within the framework of fractional plasticity to delineate the coupling between inelastic deformation and damage of quasi-brittle materials. Faced with the common challenge of determining plastic flow direction, we resort herein to the Riemann–Liouville definition of fractional derivatives, instead of introducing an additional plastic potential. The pre-peak hardening behavior is described using an exponential function, while the post-peak softening response is viewed as the consequence of material damage. For describing damage evolution, a damage criterion is constructed in terms of plastic volume dilation related to micro-crack growth. This is conducive to supply a new insight for describing the complex influence of the non-orthogonality of plastic flow on damage evolution. For numerical applications, a semi-implicit return mapping algorithm is proposed. The predictive performance of the model is evaluated by comparing numerical simulations with experimental data under various loading paths.

Permeability measurements were made on sandstone during confined Brazilian strength tests. The test involves 50 mm diameter disk-shaped, jacketed samples that are subjected to confining stresses while they are diametrically loaded. Specially designed end caps allow for concurrent gas flow measurements. The test configuration allows for the samples to be subjected to a range of stresses, with the confining stress as the intermediate principal stress. The majority of the tests measured permeability during loading to failure in the confined extension region. The permeability of the sandstone sample increases significantly well before the peak load is reached due to newly formed microcracks that continue to coalesce and dilate with further loading. Permeability increases are inversely proportional to the intermediate principal stress as increased confining pressures suppress growth, coalescence, and dilation of microcracks. Additional testing includes unloading and reloading cycles prior to failure. With each unloading–reloading cycle, permeability at comparable stresses is increased compared to the previous cycle, consistent with increasing damage in the form of an expanding microcrack network.

Dilatació aòrtica; Aneurisma de l'aorta ascendent; Anàlisi espai-temporal Dilatación aórtica; Aneurisma de la aorta ascendente; Análisis espacio-temporal Aortic dilation; Ascending aorta aneurysm; Spatiotemporal analysis Motivated by the evidence that the onset and progression of the aneurysm of the ascending aorta (AAo) is intertwined with an adverse hemodynamic environment, the present study characterized in vivo the hemodynamic spatiotemporal complexity and organization in human aortas, with and without dilated AAo, exploring the relations with clinically relevant hemodynamic and geometric parameters. The Complex Networks (CNs) theory was applied for the first time to 4D flow magnetic resonance imaging (MRI) velocity data of ten patients, five of them presenting with AAo dilation. The time-histories along the cardiac cycle of velocity-based quantities were used to build correlation-based CNs. The CNs approach succeeded in capturing large-scale coherent flow features, delimiting flow separation and recirculation regions. CNs metrics highlighted that an increasing AAo dilation (expressed in terms of the ratio between the maximum AAo and aortic root diameter) disrupts the correlation in forward flow reducing the correlation persistence length, while preserving the spatiotemporal homogeneity of secondary flows. The application of CNs to in vivo 4D MRI data holds promise for a mechanistic understanding of the spatiotemporal complexity and organization of aortic flows, opening possibilities for the integration of in vivo quantitative hemodynamic information into risk stratification and classification criteria. Open access funding provided by Politecnico di Torino within the CRUI-CARE Agreement.

It is shown that Bullet Physics Engine can be used for Discrete Element modeling of powder spreading during additive manufacturing by binder jetting. It is known that, due to technological restrictions, the thickness of deposited layers during binder jetting should not exceed several powder particle diameters making the application of continuum models of powder medium behavior to be problematic. Discrete element modeling provides the detailed information on powder behavior during powder spreading. The conducted modeling shows that dilation of the deposited powder and distortion of previously deposited layers depend on the amount of powder that is removed during spreading, on the thicknesses of the deposited layers, and on the dimensions of the manufactured components. An empirical equation describing the distortion strain as a function of powder spreading parameters is suggested as an approximation of the numerical modeling results. The main trends in green body distortion under powder spreading are experimentally validated.

The variations among shapes, sizes, and locations of tumors are obstacles for accurate automatic segmentation. U-Net is a simplified approach for automatic segmentation. Generally, the convolutional or the dilated convolutional layers are used for brain tumor segmentation. However, existing segmentation methods of the significant dilation rates degrade the final accuracy. Moreover, tuning parameters and imbalance ratio between the different tumor classes are the issues for segmentation. The proposed model, known as Residual-Dilated Dense Atrous-Spatial Pyramid Pooling (RD2A) 3D U-Net, is found adequate to solve these issues. The RD2A is the combination of the residual connections, dilation, and dense ASPP to preserve more contextual information of small sizes of tumors at each level encoder path. The multi-scale contextual information minimizes the ambiguities among the tissues of the white matter (WM) and gray matter (GM) of the infant’s brain MRI. The BRATS 2018, BRATS 2019, and iSeg-2019 datasets are used on different evaluation metrics to validate the RD2A. In the BRATS 2018 validation dataset, the proposed model achieves the average dice scores of 90.88, 84.46, and 78.18 for the whole tumor, the tumor core, and the enhancing tumor, respectively. We also evaluated on iSeg-2019 testing set, where the proposed approach achieves the average dice scores of 79.804, 77.925, and 80.569 for the cerebrospinal fluid (CSF), the gray matter (GM), and the white matter (WM), respectively. Furthermore, the presented work also obtains the mean dice scores of 90.35, 82.34, and 71.93 for the whole tumor, the tumor core, and the enhancing tumor, respectively on the BRATS 2019 validation dataset. Experimentally, it is found that the proposed approach is ideal for exploiting the full contextual information of the 3D brain MRI datasets.

This study aims at proposing a reasonable roughness parameter that can reflect the peak shear strength (PSS) of rock joints. Firstly, the contribution of the asperities with different apparent dip angles to shear strength is studied. Then the shear strength of the entire joint asperities is derived. The results showed that the PSS of the entire joint asperities is proportional to a key parameter θτ, which is related to the geometric character of the joint surface and the joint material properties. The parameter θτ is taken as the new roughness parameter, and it is reasonable to associate the PSS with the geometric characteristics of the joint surface. Based on the new roughness parameter and shear test results of 20 sets of joint specimens, a new PSS model for rock joints is proposed. The new model is validated with the artificial joints in this paper and real rock joints in published studies. Results showed that it is suitable for different types of rock joints except for gneiss joints. The new model has the form of the Mohr-Coulomb model, which can directly reflect the relationship between the 3D roughness parameters and the peak dilation angle.

Stroke is an acute cerebral vascular disease that is likely to cause long-term disabilities and death. Immediate emergency care with accurate diagnosis of computed tomographic (CT) images is crucial for dealing with a hemorrhagic stroke. However, due to the high variability of a stroke's location, contrast, and shape, it is challenging and time-consuming even for experienced radiologists to locate them. In this paper, we propose a U-net based deep learning framework to automatically detect and segment hemorrhage strokes in CT brain images. The input of the network is built by concatenating the flipped image with the original CT slice which introduces symmetry constraints of the brain images into the proposed model. This enhances the contrast between hemorrhagic area and normal brain tissue. Various Deep Learning topologies are compared by varying the layers, batch normalization, dilation rates, and pre-train models. This could increase the respective filed and preserves more information on lesion characteristics. Besides, the adversarial training is also adopted in the proposed network to improve the accuracy of the segmentation. The proposed model is trained and evaluated on two different datasets, which achieve the competitive performance with human experts with the highest location accuracy 0.9859 for detection, 0.8033 Dice score, and 0.6919 IoU for segmentation. The results demonstrate the effectiveness, robustness, and advantages of the proposed deep learning model in automatically hemorrhage lesion diagnosis, which make it possible to be a clinical decision support tool in stroke diagnosis.

Background In our study, we sought to analyse the mid-term results after interventional aortic coarctation (CoA) stenting with sequential dilation of the stent. Methods The data of all 218 patients, who are above the age of 6 years and underwent CoA-stent implantation in our hospital, were retrospectively analysed on the rate of re-interventions, complications and arterial hypertension at a follow-up time of 31 months. To avoid any aortic complications, stents were deployed primarily not in full size and a second cardiac catheterisation for further dilatation was scheduled within 6–12 months after the stent implantation. Results The median peak invasive systolic pressure gradient declined significantly from 26.2 mmHg to 2.7 mmHg after stenting. There was one procedure related death due to an aortic rupture after stent implantation. There were in total 33 (15.1%) procedure-related complications including femoral artery complications, stent fracture and stent dislocation (in 9, 9 and 7 patients, respectively). In 85 patients a re-dilatation and in 25 patients a second stent-implantation was necessary at the first re-intervention. The systolic blood pressure declined significantly from 144 mmHg to 131 mmHg after stenting. The number of patients being normotensive changed from 18% before stenting to 78.5% after stenting with adjusted antihypertensive medication. Conclusion Aortic stenting is an effective means for CoA treatment. With sequential dilation of the stent, a very low rate of life-threatening procedural complications and mortality can be achieved. CoA stenting with proper antihypertensive medications results in better control of blood pressure.

Cemented paste backfill (CPB) has been widely used as local and regional underground support to reduce host rock wall closure in mined-out areas and also to reduce rockfall and rockburst incidents. However, analyzing the rock mass—CPB interactions in the first month after backfill placement must account for the CPB’s time-dependent strength, stiffness, and volume change characteristics during binder hydration. This article presents the first such comprehensive study made for CPB from the Williams mine in Ontario, Canada. Monotonic isotopically consolidated drained compressive triaxial tests were conducted on cured CPB specimens using the lubricated-ends test technique. The specimens had 3.0–7.5% Cement Content (CC); Curing Times (CTs) were from 3 to 28 days; and the confining stress ranged from 25 to 350 kPa. During shearing, all tests exhibited an initial contractive phase leading to a Characteristic State (CHS or point of volumetric strain reversal) followed by dilation with a maximum dilation rate corresponding to peak stress at the Failure State (FS). Both CHS and FS are adequately described by the Mohr–Coulomb criterion and a framework formulation was proposed to predict the evolution of CHS and FS based on CC and CT. Furthermore, the volumetric strains at CHS and FS can be defined as linear functions of the respective axial strains at the CHS and FS. Quantification of the observed behaviors through these functional relationships can help develop future constitutive models that better represent CPB’s transient response to triaxial stress loading while curing, which is essential to understanding as-placed backfill properties and its interaction with surrounding rock mass.

In this paper, a novel two-stage R-CNN network called ParallelNet is proposed for thigh fracture detection task. In the proposed method, multiple parallel backbone networks and a feature fusion connection structure are designed, which can extract features with different reception fields. Specifically, the first backbone network is denoted as main network, which adopted normal convolution to detect small fractures, the rest backbone networks are denoted as sub-networks which adopted dilated convolution to detect large fractures. We evaluated the proposed method on a thigh fracture dataset containing 3842 X-ray radiographs, 3484 of which is assigned as a training dataset and 358 as a testing dataset. The experiments compare the proposed method with other state-of-the-art deep learning frameworks, including Faster R-CNN, FPN, Cascade R-CNN and RetinaNet, especially DCFPN which focus on thighbone fracture detection task. Our framework achieved 87.8% AP50 and 49.3% AP75 which outperformed other state-of-the-art frameworks. Moreover, ablation experiments on the backbone numbers, connection styles, different dilation rates and the position of dilated convolution have been attempted, and the function of each hyperparameter is analyzed.

Tie bars axial force demands due to concrete dilation and prying action were investigated through numerical studies. In the first part of this study, the Karagozian and Case Concrete model, which proved to provide reasonable in-plane flexural cyclic inelastic wall response while accounting for concrete dilation effect, was used to investigate the variation of confinement inside the infill concrete, the distribution of passive confining pressures at the steel–concrete interface, and the resulting tie bar axial force demands. Finite element analyses involving C-PSW/CF having different tie spacings, wall depths, and wall thicknesses were performed. In the second part of this study, the influence of plate local buckling on tie bar axial force demand was investigated and explained by prying action. A separate finite element study was performed to investigate the significance of prying action and equations were developed from free-body diagrams. The results showed the significance of the passive confining pressures due to concrete dilation, and prying action due to local plate buckling, on imparting axial forces in tie bars. Neither of these behavior are currently considered as design parameters for tie bars. The numerical analyses and results presented here are intended to provide useful insights and direction for the design and instrumentation of future C-PSW/CF experiments by the broader research community.

This paper proposes a technique for processing handwriting images. The algorithm used in this study is an improvement to the binarisation process. The enhancement focuses on correcting damaged lines that usually arise during the binarisation process, particularly, spurious holes, discontinuities, and eroded boundaries. The presented method uses a morphogical dilation operation in which a structural element is locally adapted using the information from a directional field. The adaptation process involves a new criterion for selecting orientation and shape of a structural element that combines directional field, a coherence measure, and a circular histogram. The field was computed using gradient-based approach, and a method based on a Hessian matrix. During experiments, our method was applied to the output of selected binarisation algorithms. The experiments were conducted on grayscale signature images (from the CEDAR database) and handwriting images (from the DIBCO database). The results of the algorithm were compared to the results of standard morphological operations (dilation, erosion, opening, and closing) and median filtering. The experiments show that the proposed method achieves significant accuracy improvement (8%–12% for Acc, 15%–32% for Acc2 measures), reduces the number of unwanted artefacts, and produces images with less distortion compared to those from standard approaches.

For the accurate design of geotechnical structures subjected to static and dynamic loadings, precise estimation of elastic wave velocities and hence, small strain stiffness of soil is essential. However, the interpretation of elastic wave velocities propagating in deformed/sheared soil has not been comprehensively explored. In this research, shear (Vs) and compression wave velocity (Vp) measurements have been undertaken on three kinds of uniformly graded sands during drained triaxial compression by keeping minor principal stress constant. Planar piezoelectric transducers have been used to overcome the limitations associated with the more commonly used bender elements, such as distortion of transducers during specimen shearing. This technical note reveals that the increase of major principal stress in the wave propagation direction has a more significant influence on Vp in comparison to Vs. The axial strain (ea) at which peak Vs is noted is comparable to the ea at which specimen dilation or phase transformation takes place. The Vs values show a substantial drop after phase transformation, although there is an increase in the mean stress level. However, Vp increases even after specimen dilation takes place, and it is the major principal stress that dictates its evolution during triaxial compression. Moreover, for a given material and initial stress level, elastic wave velocities of specimens prepared at different initial densities approach one another during shearing and later merge at a large ea.

Objectives The purpose of this study was to determine whether the mitral valve (MV) total leaflet area (TLA)-to-mitral annular area (MAA) (TLA/MAA) ratio measured using 3-dimensional (3D) transesophageal echocardiography (TEE) was associated with residual mitral regurgitation (MR) after MitraClip implantation in patients with secondary MR. Background The factors influencing the results of MitraClip implantation for secondary MR are controversial. This study hypothesized that insufficient remodeling of the mitral leaflets relative to the annular dilation may be associated with significant MR after MitraClip implantation. Methods This study included patients with secondary MR treated with MitraClips. Using 3D TEE dataset, the TLA in diastole and MAA in systole were measured with dedicated software. Results In a total cohort of 119 patients (mean age 74 ± 9 years; 61% male), significant residual MR (≥2+) was present in 43 patients (36%). In patients with significant residual MR, MAA was greater than in patients without residual MR (10.7 ± 2.4 cm2 vs. 9.0 ± 2.1 cm2; p Conclusions In patients with secondary MR, insufficient mitral leaflet remodeling relative to the annulus dilation, as reflected by a lower TLA/MAA ratio, is associated with significant residual MR after MitraClip implantation.

Computer vision algorithms are important for many areas of human activity. In particular, the number of applications related to the need to process images of real-world objects with computerized tools and the subsequent use of descriptive information in a variety of interactive and automated decision-making systems is increased. An important tool for analyzing real-world scenes are approaches to the application of stereo vision algorithms. The important step of many stereo matching algorithms is a disparity map. Depending on the content of the observed scene, part of the values on the disparity map can be immediately attributed to background values on a certain basis, or form a "natural" background, which is characterized by loss of informative data due to unacceptable error of subsequent resultant distance values. The calculated disparity map of any algorithm may contain some shortcomings in the form of discontinuities of continuous information areas caused by the complexity of shooting conditions, the impact of noise of various natures, hardware imperfections, and so on. An approach to mitigating the undesirable influence of negative factors on the resulting disparity is the use of mathematical morphology operations to process disparity maps at the post-processing stage. This paper presents information technology for increasing the content of disparity maps based on the mathematical morphology methods. The technology is based on a combination of morphological operations of erosion and dilation, which eliminates the typical problems of discontinuities of monotone regions and erroneous values on disparity maps. The proposed approach allows reducing the impact of common problems that arise during the operation of stereo matching algorithms, as well as increase the overall informativeness of disparity maps for images of real objects in the absence of partial or complete initial data on the characteristics of the observed scene. The results of testing morphological operations with disparity maps for real objects allow us to conclude about the possibility of partial restoration of areas of disparity maps with gaps in continuous information areas, as well as to reduce the impact of random anomalous values on the overall content of the disparity maps.

Background/Aims: Pancreatic strictures in chronic pancreatitis are treated using endoscopic retrograde cholangiopancreatography (ERCP) with plastic stent placement. The management of recalcitrant strictures remains a challenge, with the use of a Soehendra stent retriever or a needle knife described in case reports. Here, we discuss our experience with dilation of dominant pancreatic strictures with a 6-Fr cystotome.Methods: A retrospective review of an endoscopy database was performed to search for patients with pancreatic strictures recalcitrant to conventional methods of dilation in which a cystotome was used. Technical success was defined as the successful dilation of the stricture with plastic stent placement. Functional success was defined as substantial pain relief or resolution of pancreatic fistulae.Results: Ten patients (mean age, 30.8 years) underwent dilation of a dominant pancreatic stricture secondary to chronic pancreatitis, with a 6-Fr cystotome. Seven patients presented with pain. Three patients had pancreatic fistulae (two had pancreatic ascites and one had a pancreaticopleural fistula). The median stricture length was 10 mm (range, 5–25 mm). The head of the pancreas was the most common location of the stricture (60%). Technical and functional success was achieved in all patients. One patient had self-limiting bleeding, whereas another patient developed mild post-ERCP pancreatitis.Conclusions: The use of a 6-Fr cystotome (diathermy catheter) can be an alternative method for dilation of recalcitrant pancreatic strictures after the failure of conventional modalities.