Wire Frame Research Articles

Stenting as porous media in anatomically accurate geometries. A comparison of models and spatial heterogeneity

Modelling intracranial aneurysm blood flow after flow diverter treatment has proven to be of great scientific and clinical interest. One of the reasons for not having CFD as an everyday clinical tool yet is the time required to set-up such simulations plus the required computational time. The speed-up of these simulations can have a considerable impact during treatment planning and device selection. Modelling flow diverters as a porous medium (PM) can considerably improve the computational time. Many models have been presented in literature, but quantitative comparisons between models are scarce.In this study, the untreated case, the explicit definition of the flow diverter wires as no-slip boundary condition and five different porous medium models were chosen for comparison, and evaluated on intracranial aneurysm of 14 patients with different shapes, sizes, and locations. CFD simulations were made using finite volume method on steady flow conditions. Velocities, kinetic energy, wall shear stress, and computational time were assessed for each model. Then, all models are compared against the no-slip boundary condition using non parametric Kolmogorov–Smirnov test.The model with least performance showed a mean K-S statistic of 0.31 and deviance of 0.2, while the model with best values always gave K-S statistics below 0.2. Kinetic energy between PM models varied between an over estimation of 218.3% and an under estimation of 73.06%. Also, speedups were between 4.75x and 5.3x (stdev: 0.38x and 0.15x) when using PM models.Flow diverters can be simulated with PM with a good agreement to standard CFD simulations were FD wires are represented with no-slip boundary condition in less than a quarter of the time. Best results were obtained on PM models based on geometrical properties, in particular, when using a heterogeneous medium based on equations for flat rhomboidal wire frames.

Lower limb paediatric trauma with bone and soft tissue loss: Ortho-plastic management and outcome in a major trauma centre

AimWe examined the management and outcome of patients suffering complex paediatric lower limb injuries with bone and soft tissue loss. MethodPatients were identified from our prospective trauma database (2013-2018). Inclusion criteria were age (<18 years) and open lower-limb trauma. We assessed severity of soft tissue and/or bone loss, fracture complexity, surgical techniques and time to surgery. Paediatric quality of life and psychological trauma impact scores (HRQOL and CRIES), Ganga Hospital Injury Severity score (GHISS), union and complication rates were measured. ResultsWe identified 32 patients aged between 4 and 17 years. Twenty-nine patients had open tibia fractures including 14 patients with bone loss, one patient had an open femur fracture, one patient an open talus fracture and one an open ankle fracture with dorsal degloving. Thirty injuries were classified intra-operatively as Gustilo IIIB (or equivalent) and two injuries as Gustilo IIIC. In 10 patients primary skin closure was achieved by acute shortening following segmental bone loss. Twenty-two patients required soft tissue coverage: 17 free vascularised flaps, two fascio-cutaneous flaps and three split skin grafts were used. Two patients required vascular repair. Soft tissue coverage was achieved within 72 hours in 26 patients (81%) and within a week in 30 patients (94%). The surgical techniques applied were: circular fine wire frame (19), monolateral external fixator (4) and open reduction internal fixation (8). Median follow up time was 18 (7-65) months. Paediatric quality of life scores were available in 30 patients (91%) with a median total score of 77.2 out of 100. The psychological trauma impact scores showed one in three patients was at risk of developing post-traumatic stress symptoms (PTSD). The GHISS scores ranged from 6-13. All fractures went on to unite over a median time of 3.8 (2-10) months. Three patients (9%) had major complications; two flap failures requiring revision, one femur non-union requiring revision fixation. ConclusionLimb salvage and timely fracture union is possible in children with complex lower limb trauma. Early intervention providing adequate debridement, skeletal stabilisation and early soft-tissue cover including the option of free microvascular reconstruction in small children when required, delivers acceptable outcomes. A multidisciplinary team approach including clinical psychologists to address the psychological impact of trauma provides optimal holistic care for these children and adolescents. Therefore, treatment for these patients should only be performed in paediatric major trauma centres.

Our experience with kite string injuries during makarsankranti festival

Kite-flying is a popular activity during the Makar Sankranti festival in Gujarat which spans over 14th and 15th January of every year. Kite strings are an important cause of penetrating neck trauma in two-wheeler drivers. In this study a total of 63 patients of kite string injuries over face and neck were studied between 2018 and 2020 at Shri Sayajirao General Hospital, Vadodara. These patients were divided into 3 groups according to the site of injury. Males were most commonly affected. Most patients were in the 19-40 years age group. Neck was the most frequently involved in most of the patients. Majority of the patients did not use personal protective gears. An indigenous metal wire frame used over two-wheelers also appeared to be reducing the number of injuries. We conclude that awareness can prevent these injuries to a large extent. Keywords: Kite String, Cut Throat, Uttarayan, Makarsankranti.

Bubble entrainment by a sphere falling through a horizontal soap foam

Processes such as particle separation, froth flotation and explosion suppression rely on the extent to which particles are trapped by foam films. We simulate the quasi-static motion of a spherical particle through a stable, horizontal soap film. The soap film subtends a fixed contact angle, in the range , where it meets the particle. The tension and pressure forces acting on the particle are calculated in two cases: when the film is held within a vertical cylinder, trapping a bubble but otherwise free to move vertically, and when the outer rim of the film is held in a fixed circular wire frame. Film deformation is greater in the second case, and the duration of the interaction therefore increases, increasing the contact time between particle and film. As the soap film returns towards its equilibrium shape following the passage of the particle a small bubble is trapped for contact angles below a threshold value of 90°. We quantify how the size of this bubble increases when the particle is larger and when the contact angle is smaller.

Extracardiac Mechanical Support Device Placement by a Minimally Invasive Approach is Safe and Effective

All current short-term mechanical cardiac assist devices are placed intravascularly and are associated with relatively high rates of thrombosis and infection. We examined a non-blood-contacting extracardiac device that can be inserted with a minimally invasive technique. The CorInnova cardiac assist device consists of 2 polyurethane chambers and a nitinol wire frame. It surrounds the left and right ventricles (fig 1). Its low-profile allows actuation within the pericardium. Air chambers pressurize cyclically to compress the heart during systole. Minimally invasive implantation was assessed in ovine studies. In a beating-heart procedure under general anesthesia, cardiac access was via a 2-3 inch subxiphoid incision. A small pericardial incision was made at the cardiac apex. Under fluoroscopy, the device was advanced to surround the ventricles within the pericardial space (fig 2). After chest closure, fluid was infused into the device's innermost chamber to conform the device to the epicardium. Minimally invasive deployment and attachment was successful for 55 devices in 25 acute studies. No animal sustained any cardiac injury as confirmed by necropsy. The wire frame allowed the device to self-flare around the heart. The intact pericardium kept the device intimately attached to the myocardium. Device-heart coupling was enhanced by the fluid chamber. This feature was verified in several (25+) acute studies and one 5-day study as documented by fluoroscopic imaging and subsequent explant. A novel extracardiac assist device can be placed safely using a minimally invasive procedure.

Early clinical experience with the straight design of Venus P-valve™ in dysfunctional right ventricular outflow tracts.

To assess the initial procedural and short to medium-term experience with the straight design of the Venus P-valve™ (Venus MedTech, Hangzhou, China) in dysfunctional right ventricular outflow tracts (RVOT). The Melody™ valve (Medtronic, Minneapolis, Minnesota) has been the only percutaneous valve option for smaller RVOT conduits. The straight Venus P-valve™ may provide an alternative to the Melody™ valve. Retrospective data collection of patient characteristics, procedural data, clinical and imaging follow-up of the straight Venus P-valve™. Nine patients (four female) with a mean age of 23.1 ± 7.5 years and a mean weight of 72.7 ± 29.4 kg underwent straight Venus P-valve™ implantation between 03/2014 and 06/2016. All patients had right ventricle-to-pulmonary artery conduits which were pre-stented before the valve implantation. All valves were deployed successfully without any significant procedural complications. During the mean follow-up of 24 ± 9.1 months, there were no valve related re-interventions or deterioration in valve performance. There was one case of insignificant, single wire frame fracture and no cases of endocarditis. The cohort demonstrated a reduction in pulmonary regurgitation and tricuspid regurgitation, which was sustained throughout the follow-up. Similarly the gradient across the RVOT tract did not significantly increase. Implantation of the straight Venus P-valve™ has provided satisfactory short to mid-term results with high success rates and no complications and may be considered as an alternative option in patients with RVOT dysfunction.

Integrating digital and conventional recording techniques for the documentation and reconstruction of an 18th-Century wooden ship from Alexandria, VA

An 18th-century wooden ship discovered on the waterfront of Alexandria, Virginia was documented and modelled using laser scanning, computer modelling, 3D printing, traditional lines drawings, and wooden ship modelling techniques. This combination of new technologies and traditional ship documentation methods allowed researchers to capture the details of the ship remains with extremely high accuracy. The models of the timbers were then 3D printed, reassembled, and incorporated into an interpretive wire frame model that contextualized the remains of the ship with what it would have looked like whole.

ASSURED clinical study: New GORE® CARDIOFORM ASD occluder for transcatheter closure of atrial septal defect

Assess clinical performance of a new device for transcatheter closure of atrial septal defect (ASD). Previously-approved ASD Closure devices have known limitations. Device erosion has been associated with the AMPLATZER® septal occluder in patients with retro-aortic rim deficiency (<5 mm), while defects ≥18 mm are too large for the GORE® CARDIOFORM septal occluder. The GORE® CARDIOFORM ASD occluder (GCA), a hybrid of the approved devices, was designed to expand the eligible ASD population. One-hundred and twenty-five ASD patients were enrolled in a prospective, multicenter registry. Descriptive clinical endpoints included: technical implant success, closure success, serious adverse events (SAE), clinically significant new arrhythmia, and wire frame fracture. Procedural outcomes and adverse events were adjudicated by an Echocardiography Core Lab and Independent Data Review Board, respectively. Median subject age was 12.3 years (range 2.9-84.7), with 72% of patients ≤18 years old. Median ASD stop-flow diameter was 17.0 mm (8.0-30.0), with 43% ≥18 mm. Deficient retro-aortic rim occurred in 57% of subjects, and 30% had both diameter ≥ 18 mm and deficient rim. Technical Implant Success was achieved in 120/125 (96%), though three devices were removed within 24 hr. At the scheduled 6-month evaluation, 112/117 returned for evaluation. All 112 had closure success. SAE occurred in 6/125 (4.8%) and 6/125 (4.8%) had clinically significant new arrhythmia. Wire frame fractures occurred in 37/104 (36%), without any associated clinical sequelae, residual shunt, or device instability. The GCA performed effectively and safely in this initial cohort, and led to FDA approval based on this data.

Percutaneous Closure of Patent Foramen Ovale and Secundum Atrial Septal Defects with the GORE�CARDIOFORM Septal Occluder: Incidence and Implications of Device Wire Frame Fracture

Percutaneous Closure of Patent Foramen Ovale and Secundum Atrial Septal Defects with the GORE�CARDIOFORM Septal Occluder: Incidence and Implications of Device Wire Frame Fracture

Once a River

Once a River Daryl Farmer (bio) "It is the only way to end poverty," says El Presidente. I look at the land below us and yearn for green and blue, instead of this ash gray, dust brown. A hazy sun. My eyes burn. I have not been home for going on two hundred days. This morning, I looked in the mirror and saw my liquid eye squinting out from leathered skin. A murmuring babble coming from my lips, something about another source-become-friend now dead. People associate my name with violence, think I must like it, all the horrific acts, but I don't. I confess to be drawn to it, absorbed by it, obsessed with the way it manifests itself in the most unlikely ways. But when I left the camp, and returned to the hotel amid the ruins, I wept. There's predator and prey, which is just survival, and then there's sport, the doing that comes simply from the knowing that you can. Then there's a kind of power that's the last step before evil. Or maybe evil comes first. It seems odd to me that El Presidente is piloting this helicopter, but he likes to fly, he says, has learned to trust only what he himself controls. Information deemed classified—yet passed on to me, thereby declassifying it—shows at least seventeen assassination attempts on El Presidente. I asked him yesterday if this was true, and he seemed offended. "Surely," he said, "there have been more." I have known El Presidente for over twenty years. Our first interview was in a small hotel room, two chairs, no bed. Why? I asked him. He shrugged, said he didn't need one, had given up sleep. It was his custom, he said, to have all furniture removed wherever he stayed. He liked to pace, and if he did need to sit, he rested against a wall. The chairs in that room were a courtesy, on my account. He seemed to me then a mystic, and against my own cynicism, I found him charming, despite that charred lithified face so badly burned it reminded me of wax once dripping now hardened. I couldn't take my eyes off him. He wore wire frame specks then, the lenses magnified, so as to bring to mind a giant fly. I asked him if he'd ever considered surgery. He smiled. "And why?" he asked. "To mask all that I have survived? No, friend. My face is my history." [End Page 52] This was before the coup that had brought him to power, before the dark black glasses that would become his trademark. Too small for his face, these glasses. Now he looks not like a fly but a bespectacled snake. I am sitting in the copilot's seat. Earlier, he had offered us each a blindfold. When I refused, he'd smiled, shrugged. There are five of us. The woman sitting behind me is the wife of a commander whose name you used to see on the news, that same commander who now sits in a federal prison for a betrayal against immorality. Crime of all crimes, he told the truth, finally. Sometimes treason is just a man with a conscience, though he found his a little too late. Last night, I saw her, the wife, sitting alone in a corner of the hotel bar. I noticed she was crying. That is to say, tears streamed down her face, but she stared straight ahead with that distant look that I had heretofore only seen in soldiers, victims. Now that look is everywhere. A longing for a home that would never again exist for her. I walked to the table, meant to offer her some kindness, not knowing what that might even be. "Fuck off," she'd said, without looking at me. I had left her to her horrors. Today, when offered the blindfold, she had taken it without a word. She wears it now, though we are many miles from the refugee camp. The people who end there will have walked over a hundred starving miles. It is estimated that only about 37 percent of those who...

Characteristic Identification Methodology for 2D Sheet Metal Components

In the computer-integrated production environment, computer-assisted process planning is a key area which analyses the Computer aided Design server collects information about design and converts it into the necessary information about manufacturing. To identify 2D sheet shearing operations from the nested architecture provided by a wire frame template, a feature identification procedure has been suggested. Basically, the method uses geometric data to determine different groups of objects. Entity groups are categorized into a number of features for raw resources, a set of boundary features, and a set of interior features. There seems to be a special classification of the feature functions inclusion to both the set of boundary functions. Components (i.e. boundary elements set together with their inside feature set components) are lexicographically arranged. Based on the suggested categorization for shearing practices and using multiple feature sets, processing features were defined. The technique listed above, definitions are explained along with its principles. This is performed in the C environment and from the DXF output directory of AutoCAD geometric information is retrieved..

Two cases of pericardial tamponade due to nitinol wire fracture of a gore septal occluder

Percutaneous patent foramen ovale (PFO) closure is recommended for secondary prevention of paradoxical embolism through a PFO. In the United States, two Food and Drug Administration-approved PFO closure devices are currently available, and the choice depends on operator preference and PFO anatomy. Although these devices are easy to implant, there are several potential complications. As opposed to the Amplatzer PFO Occluder, there has been no published case of atrial erosion with Gore closure devices. This report describes two cases of pericardial tamponade due to perforation of the atrial wall induced by a wire frame fracture of the Gore Helex and Cardioform devices.

Quantitative Stent Graft Motion in ECG Gated CT by Image Registration and Segmentation: In Vitro Validation and Preliminary Clinical Results

The dynamic endovascular environment of stent grafts may influence long term outcome after endovascular aneurysm repair (EVAR). The sealing and fixation of a stent graft to the aortic wall is challenged at every heartbeat, yet knowledge of the cardiac induced dynamics of stent grafts is sparse. Understanding the stent-artery interaction is crucial for device development and may aid the prediction of failure in the individual patient. The aim of this work was to establish quantitative stent graft motion in multiphasic electrocardiogram (ECG) gated computed tomography (CT) by image registration and segmentation techniques. Experimental validation was performed by evaluating a series of ECG gated CT scans of a stent graft moving at different amplitudes of displacement at different virtual heart rates using a motion generating device with synchronised ECG triggering. The methodology was further tested on clinical data of patients treated with EVAR devices with different stent graft designs. Displacement during the cardiac cycle was analysed for points on the fixating stent rings, the branches or fenestrations, and the spine. Errors for the amplitude of displacement measured invitro at individual points on the wire frame were at most 0.3mm. In situ cardiac induced displacement of the devices was found to differ per location and also depended on the type of stent graft. Displacement during the cardiac cycle was greatest in a fenestrated device and smallest in a chimney graft sac anchoring endosystem, with maximum displacement varying from 0.0 to 1.4mm. There was no substantial displacement measurable in the spine. A novel methodology to quantify and visualise stent graft motion in multiphasic ECG gated CT has been validated invitro and tested invivo. This methodology enables further exploration of in situ motion of different stent grafts and branch stents and their interaction with native vessels.

New Product Design with Automatic Scheme Generation

Traditionally, design schemes were usually drawn manually or with the help of graphics software. These methods are usually labor-intensive and time-consuming. The design field calls for advanced product design, which will be highly efficient and meet more individualized demands for customized manufacturing. In this paper, a new design approach is introduced to assist designers to improve the efficiency of product design with automatic sample generation algorithms. This approach mainly consists of two parts: design scheme generation and sketch inversion. For design scheme generation, we adopt the generative adversarial networks to extract features from the existing product images and generate new design schemes based on these features. This is followed by post-processing including wire frame design and sketch design. Meanwhile, for sketch inversion, the sketches are generated and input along with the corresponding color images to train the sketch inversion model. With this model, hand-drawn sketches are transferred into color design schemes. We take watch designing as an example to validate the effectiveness of the proposed method on design scheme generation and sketch inversion. Experimental results demonstrate that the proposed design scheme generation method can generate new product design schemes, and further sketch inversion process can transfer them into color design schemes with high quality.

Designing, Modelling and Analysis of The Edge Geometry of Linear Lathe Tool Bit

In this publication, with the help of our modelling software we have designed and modelled the edge geometry of the linear lathe tool in the model space. Our aim has been to develop a program which calculates the appropriate edge geometry with the help of some input length and angle dimensions. This is modelled in a wire frame model in a kind a file format that can be easily opened in the latest CAD softwares – so if some later modifications are needed, that can be done easily on the model. With the help of Finite Element Simulation based on given loads, boundary conditions, technological parameters and material quality, an optimal edge geometry can be determined on the cutting tool for reaching the best cutting ratio.

Soap films with gravity and almost-minimal surfaces

Motivated by the study of the equilibrium equations for a soap film hanging from a wire frame, we prove a compactness theorem for surfaces with asymptotically vanishing mean curvature and fixed or converging boundaries. In particular, we obtain sufficient geometric conditions for the minimal surfaces spanned by a given boundary to represent all the possible limits of sequences of almost-minimal surfaces. Finally, we provide some sharp quantitative estimates on the distance of an almost-minimal surface from its limit minimal surface.

Novel Miniature Tip Design for Enhancing Dexterity in Minimally Invasive Surgery

Even though technological advances have increased the application area of minimally invasive surgery (MIS), there are still hurdles to allow for widespread adoption for more complex procedures. The development of steerable instruments, in which the surgeon can alter the tip orientation, has increased the application area of MIS, but they are bulky, which limits their ability to navigate through narrow environments, and complex, which complicates miniaturization. Furthermore, they do not allow for navigating through complex anatomies. In an effort to improve the dexterity of the MIS instruments, while minimizing the outer dimensions, the previously developed cable-ring mechanism was redesigned, resulting in the thinnest, Ø 2 mm (Ø 1 mm lumen), eight degrees-of-freedom (DOF) multisteerable tip for MIS to date. The multisteerable tip consists of four steerable segments of 2DOF stackable elements allowing for ±90 deg articulation, as well the construction of complex shapes, actuated by 16 Ø 0.2 mm stainless steel cables. In a proof-of-principle experiment, an ultrasound transducer and optical shape sensing (OSS) fiber were inserted in the lumen, and the multisteerable tip was used to perform scanning motions in order to reconstruct a wire frame in three-dimensional (3D). This configuration could in future be used to safely navigate through delicate environments and allow for tissue characterization. Therefore, the multisteerable tip has the potential to increase the application area of MIS in future, as it allows for improved dexterity, the ability to guide several tip tools toward the operation area, and the ability to navigate through tight anatomies.

Comparing case-control study for treatment of proximal tibia fractures with a complete metaphyseal component in two centers with different distinct strategies: fixation with Ilizarov frame or locking plates

BackgroundThe purpose of this study was to compare two methods of stabilization for proximal tibia fractures (AO 41) with a complete metaphyseal component, external fixation with the Ilizarov wire frame, and internal fixation with locking plates.MethodsPatients from two level 1 trauma centers treated between 2009 and 2015 were included in a retrospective comparing cohort study. The first center stabilized the non-pathological, proximal tibia fractures exclusively with external fixation and the second with internal plating. Combined clinically and radiologically evaluated, bone healing was the primary outcome. The secondary outcomes included complications, range of motion (ROM) and axial alignment of the knee, the reoperation rate within 6 months, heterotopic ossifications (HTO), and signs of posttraumatic osteoarthritis (PTOA). A logistic regression analysis corrected for uneven distributed parameters.ResultsThe 62 patients treated with Ilizarov frame and the 68 patients treated with plate fixation were comparable regarding epidemiological parameters, injury characteristics, and comorbidity except for injury severity score (ISS) and smoking behavior. The time of healing was shorter in the group undergoing plate fixation (p = 0.041); however, the incidence of non-unions was equal. Furthermore, there was no difference regarding the rate of deep infections, thrombosis, alignment, reoperations, PTOA, and ROM. Heterotopic ossifications were more prevalent following plate fixation (13.2 vs 1.6%, p = .013). External fixation was associated with a higher rate of superficial infections (40.4 vs 2.9%, p = .000). The initial displacement, the incidence of deep infections, and the classification significantly influenced the incidence of non-unions in both groups (p < 0.02).ConclusionsFixation of proximal tibia fractures with plates resulted in a slightly shorter healing time compared to Ilizarov frame stabilization. Furthermore, the complication profiles differ with more heterotopic ossifications and less superficial infections following internal plating.Trial registrationDRKS, DRKS00013275, Registered 11/2/2017, Retrospectively registered.

Computer-aided inverse panorama on a conical projection surface

The aim of this study is to develop a practical method of direct mapping of an inverse conical panorama with computer aid. The panoramic image is a central projection onto a conical surface from the centres dispersed on a circular or straight path located outside the projection surface. The proposed method is a nonlinear projection in which the resulting image is treated as a sequence of stitched pictures of zero width taken from a moving view point. Geometric data and relations between the projected points are utilised to formulate algorithms for drawing of inverse panoramic images of straight lines, which further enables drawing of wire frame models of represented forms. Images are drawn as plots of a function in the Mathcad software. However, in order to make drawing more efficient and convenient, as well as for the practical applications of them, the algorithms can be implemented in any graphical package.

Visualization of CAD and CAE Files using VTK and MFC

This software is capable of reading the file formats like - .OBJ, .WRL, .STL, .STEP, .IGES and 3D scenes can be rendered with an inclusion of the properties viz. applying variousLights, Material Color, and Options for Solid, Wire frame, Points and Transparency viewing, Texture Mapping, Transformation, Walkthrough, Cut Sections, Background color selection, Background and Base image selection, Markup features such as Sealing and Measurements, Different camera views, Parts selection and deletion, Copying the rendered object to the clipboard and enabling to view more than one models through multiple tabbed windows.Stereovision feature has been added to this software, which gives better 3D visual effect at lower cost. This software is also intended to incorporate ease of use and portability so that it can run on any low end workstation having windows operating system.