scholarly journals The evolution of triple junctions: from failure to success

2021 ◽  
Author(s):  
Hany Khalil ◽  
Fabio Capitanio ◽  
Alexander Cruden
Keyword(s):  
Triple Junction ◽  
Early Stage ◽  
Three Dimensional ◽  
Triple Junctions ◽  
Continental Rifting ◽  
Strain Gradients ◽  
Strain Jump ◽  
Spreading Ridges ◽  
Boundary Rotation ◽  
Analog Experiments

Divergent triple junctions are stable plate margins where three spreading ridges meet. Although it is accepted that this configuration is inherited from an earlier phase of continental rifting, how post-breakup triple junctions emerge from the separation of two plates remains unclear. By documenting the strain rate history recorded in the three rift-arms of several modern and ancient triple junctions, we show that deformation is episodic and localized in only one or two rifts at any given time. We further investigate this behavior in three-dimensional (3D) analog experiments of rifting, under a range of kinematic boundary conditions and containing a variety of pre-existing lithospheric heterogeneities. Deformation in the experiments is characterized by strain jumps and rift abandonment, comparable to natural observations. Boundary rotation during extension induces oblique stretching directions, along-strike strain gradients and forces significant strain jump to reduce the number of rifts segments active. Models that comprise lithospheres ranging from homogenous to containing a triple junction-like pre-existing heterogeneities, never developed a three-armed rift, where all rift segments are active at same time, at any stage. Our experimental results indicate that, unlike mature, successful, and stable oceanic triple junctions, early-stage continental rifting progresses through unstable “double-junctions” characterized by repeated strain jumps and rift failures and reactivations.

Evolution of Triple Junctions

1975 ◽  
Vol 12 (3) ◽  
pp. 516-519 ◽  
Author(s):  
Derek York
Keyword(s):  
Triple Junction ◽  
Angular Spread ◽  
Triple Junctions ◽  
Central Pacific ◽  
East Central ◽  
Spreading Ridges

The condition for stability at a triple junction of three normally spreading ridges should read: all ridge orientations may be stable if and only if the three ridge elements occupy an angular spread of more than 180°. This consideration leads to the conclusion that, in one mode of formation of an RRR triple junction, at least one active ridge segment should be extinguished. A fossil rise in the east-central Pacific is examined as a possible illustration of the argument.

scholarly journals Organ motion in linac-based SBRT for glottic cancer

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Annarita Perillo ◽  
Valeria Landoni ◽  
Alessia Farneti ◽  
Giuseppe Sanguineti
Keyword(s):  
Early Stage ◽  
Displacement Vector ◽  
Thyroid Cartilage ◽  
Three Dimensional ◽  
Target Volume ◽  
Glottic Cancer ◽  
Organ Motion ◽  
Delivery Times ◽  
Significant Difference ◽  
Pre Treatment

Abstract Purpose The purpose of this study is to evaluate inter- and intra-fraction organ motion as well as to quantify clinical target volume (CTV) to planning target volume (PTV) margins to be adopted in the stereotactic treatment of early stage glottic cancer. Methods and materials Stereotactic body radiotherapy (SBRT) to 36 Gy in 3 fractions was administered to 23 patients with early glottic cancer T1N0M0. Patients were irradiated with a volumetric intensity modulated arc technique delivered with 6 MV FFF energy. Each patient underwent a pre-treatment cone beam computed tomography (CBCT) to correct the setup based on the thyroid cartilage position. Imaging was repeated if displacement exceeded 2 mm in any direction. CBCT imaging was also performed after each treatment arc as well as at the end of the delivery. Swallowing was allowed only during the beam-off time between arcs. CBCT images were reviewed to evaluate inter- and intra-fraction organ motion. The relationships between selected treatment characteristics, both beam-on and delivery times as well as organ motion were investigated. Results For the population systematic (Ʃ) and random (σ) inter-fraction errors were 0.9, 1.3 and 0.6 mm and 1.1, 1.3 and 0.7 mm in the left-right (X), cranio-caudal (Y) and antero-posterior (Z) directions, respectively. From the analysis of CBCT images acquired after treatment, systematic (Ʃ) and random (σ) intra-fraction errors resulted 0.7, 1.6 and 0.7 mm and 1.0, 1.5 and 0.6 mm in the X, Y and Z directions, respectively. Margins calculated from the intra-fraction errors were 2.4, 5.1 and 2.2 mm in the X, Y and Z directions respectively. A statistically significant difference was found for the displacement in the Z direction between patients irradiated with > 2 arcs versus ≤ 2 arcs, (MW test, p = 0.038). When analyzing mean data from CBCT images for the whole treatment, a significant correlation was found between the time of delivery and the three dimensional displacement vector (r = 0.489, p = 0.055), the displacement in the Y direction (r = 0.553, p = 0.026) and the subsequent margins to be adopted (r = 0.626, p = 0.009). Finally, displacements and the subsequent margins to be adopted in Y direction were significantly greater for treatments with more than 2 arcs (MW test p = 0.037 and p = 0.019, respectively). Conclusions In the setting of controlled swallowing during treatment delivery, intra-fraction motion still needs to be taken into account when planning with estimated CTV to PTV margins of 3, 5 and 3 mm in the X, Y and Z directions, respectively. Selected treatments may require additional margins.

scholarly journals Mobile three-dimensional visualisation technologies for clinician-led fall prevention assessments

2017 ◽  
Vol 25 (3) ◽  
pp. 788-810 ◽  
Author(s):  
Julian Hamm ◽  
Arthur G Money ◽  
Anita Atwal ◽  
Gheorghita Ghinea
Keyword(s):  
Early Stage ◽  
Three Dimensional ◽  
Occupational Therapists ◽  
Structured Interview ◽  
Future Research ◽  
Dimensional Measurement ◽  
Fall Risk Factors ◽  
System Usability Scale ◽  
Process Guidance ◽  
Three Dimensional Measurement

The assistive equipment provision process is routinely carried out with patients to mitigate fall risk factors via the fitment of assistive equipment within the home. However, currently, over 50% of assistive equipment is abandoned by the patients due to poor fit between the patient and the assistive equipment. This paper explores clinician perceptions of an early stage three-dimensional measurement aid prototype, which provides enhanced assistive equipment provision process guidance to clinicians. Ten occupational therapists trialled the three-dimensional measurement aid prototype application; think-aloud and semi-structured interview data was collected. Usability was measured with the System Usability Scale. Participants scored three-dimensional measurement aid prototype as ‘excellent’ and agreed strongly with items relating to the usability and learnability of the application. The qualitative analysis identified opportunities for improving existing practice, including, improved interpretation/recording measurements; enhanced collaborative practice within the assistive equipment provision process. Future research is needed to determine the clinical utility of this application compared with two-dimensional counterpart paper-based guidance leaflets.

Increase in Tibial Internal Rotation Due to Weight-bearing is a Key Feature to Diagnose Early-stage Knee Osteoarthritis: A Study with Upright Computed Tomography

2021 ◽  
Author(s):  
Kazuya Kaneda ◽  
Kengo Harato ◽  
Satoshi Oki ◽  
Yoshitake Yamada ◽  
Masaya Nakamura ◽  
...  
Keyword(s):  
Knee Osteoarthritis ◽  
Internal Rotation ◽  
Early Stage ◽  
Weight Bearing ◽  
Three Dimensional ◽  
Surface Registration ◽  
Lower Limbs ◽  
Clinical Issue ◽  
Osteoarthritic Change ◽  
Tibial Internal Rotation

Abstract Background The classification of knee osteoarthritis is an essential clinical issue, particularly in terms of diagnosing early knee osteoarthritis. However, the evaluation of three-dimensional limb alignment on two-dimensional radiographs is limited. This study evaluated the three-dimensional changes induced by weight-bearing in the alignments of lower limbs at various stages of knee osteoarthritis.Methods 45 knees of 25 patients (69.9 ± 8.9 years) with knee OA were examined in the study. CT images of the entire leg were obtained in the supine and standing positions using conventional CT and 320 low-detector upright CT, respectively. Next, the differences in the three-dimensional alignment of the entire leg in the supine and standing positions were obtained using 3D-3D surface registration technique, and those were compared for each Kellgren–Lawrence grade. Results Increased flexion, adduction, and tibial internal rotation were observed in the standing position, as opposed to the supine position. Kellgren–Lawrence grades 1 and 4 showed significant differences in flexion, adduction, and tibial internal rotation between two postures. Grades 2 and 4 showed significant differences in adduction, while grades 1 and 2, and 1 and 3 showed significant differences in tibial internal rotation between standing and supine positions.Conclusions Weight-bearing increased the three-dimensional deformities in knees with osteoarthritis. Particularly, increased tibial internal rotation was observed in patients with grades 2 and 3 compared to those with grade 1. The increase in tibial internal rotation due to weight-bearing is a key pathologic feature to detect early osteoarthritic change in knees undergoing osteoarthritis.

scholarly journals Strength Characteristics and the Reaction Mechanism of Stone Powder Cement Tailings Backfill

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Jianhua Hu ◽  
Qifan Ren ◽  
Quan Jiang ◽  
Rugao Gao ◽  
Long Zhang ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Early Stage ◽  
Low Cost ◽  
Three Dimensional ◽  
Adsorbed Water ◽  
Gelling Agent ◽  
Hydration Reaction ◽  
3D Network ◽  
Mining Procedure ◽  
Powder Content

Stone powder cement (SPC) is widely used as a novel cement substitute material in concrete for its good gelling performance and low cost. In order to reduce the backfilling cost and assess the potential of SPC backfilling materials, a series of experiments were conducted to analyze the strength and hydration reaction mechanism of stone powder cement tailings backfill (SPCTB). The analysis was based on SPC and tailings, which were used as the gelling agent and the aggregate, respectively. The results showed that the strength of the backfill was greatly reduced at an early stage and slightly reduced in the final stages. The stone powder content was less than 15%, which met the requirement of mining procedure. The addition of stone powder reduced the content of adsorbed water and capillary water in the early stages, while it increased in the middle stages. The SiO2 contained in stone powder reacted with the hydration products at later stages, which is the reason why the growth of strength is rapid between the groups with the addition of stone powder. The addition of stone powder improved the microstructure of backfill and produced a denser three-dimensional (3D) network structure; however, the plane porosities of Groups A and B gradually increased with the increase in the content of stone powder. The cement powder mixed appropriately with the stone power could meet the strength requirement and reduce the cost of backfilling materials.

Parametric geometry model design of a wingsuit

2020 ◽  
Vol 32 (5) ◽  
pp. 691-705
Author(s):  
Nazanin Ansari ◽  
Sybille Krzywinski
Keyword(s):  
Computer Aided Design ◽  
Early Stage ◽  
Three Dimensional ◽  
Production Costs ◽  
Process Chain ◽  
Content Type ◽  
Geometry Model ◽  
Computer Aided ◽  
2D Pattern ◽  
Aided Design

PurposeThis paper aims to introduce a process chain spanning from scanned data to computer-aided engineering and further required simulations up to the subsequent production. This approach has the potential to reduce production costs and accelerate the procedure.Design/methodology/approachA parametric computer-aided design (CAD) model of the flyer wearing a wingsuit is created enabling easy changes in its posture and the wingsuit geometry. The objective is to track the influence of geometry changes in a timely manner for following simulation scenarios.FindingsAt the final stage, the two-dimensional (2D) pattern cuts were derived from the developed three-dimensional (3D) wingsuit, and the results were compared with the conventional ones used in the first stages of the wingsuit development.Originality/valueProposing a virtual development process chain is challenging; apart from the fact that the CAD construction of a wingsuit flyer – in itself posing a complicated task – is required at a very early stage of the procedure.

Backbone dihedral angles prediction servers for protein early-stage structure prediction

2019 ◽  
Vol 15 (4) ◽  
Author(s):  
Tomasz Smolarczyk ◽  
Katarzyna Stapor ◽  
Irena Roterman-Konieczna
Keyword(s):  
Protein Folding ◽  
Secondary Structure ◽  
Protein Function ◽  
Structure Prediction ◽  
Secondary Structure Prediction ◽  
Early Stage ◽  
Three Dimensional ◽  
Stage Structure ◽  
Dihedral Angles ◽  
Starting Point

AbstractThree-dimensional protein structure prediction is an important task in science at the intersection of biology, chemistry, and informatics, and it is crucial for determining the protein function. In the two-stage protein folding model, based on an early- and late-stage intermediates, we propose to use state-of-the-art secondary structure prediction servers for backbone dihedral angles prediction and devise an early-stage structure. Early-stage structures are used as a starting point for protein folding simulations, and any errors in this stage affect the final predictions. We have shown that modern secondary structure prediction servers could increase the accuracy of early-stage predictions compared to previously reported models.

scholarly journals Evaluation of a Balloon-Type Vaginal Endoscope Based on Three-Dimensional Printing Technology for Self-Assessment of Pelvic Organ Prolapse

2020 ◽  
Vol 10 (15) ◽  
pp. 5108
Author(s):  
Myoungjae Jun ◽  
Hieyong Jeong ◽  
Masayuki Endo ◽  
Michiko Kodama ◽  
Yuko Ohno
Keyword(s):  
Pelvic Organ Prolapse ◽  
Early Stage ◽  
Low Cost ◽  
Three Dimensional ◽  
Evaluation Study ◽  
Pelvic Organ ◽  
Self Assessment ◽  
Overweight Women ◽  
Depth Sensors ◽  
Feasibility Evaluation

Pelvic organ prolapse (POP) can occur if the support tissues or the pelvic floor muscles are weakened and damaged. There is increased probability for POP occurrence after childbirth, menopause, or in overweight women. Because the natural history and progression of POP is still unknown, the approaches used to prevent it have not been clear. POP is an uncomfortable condition that affects one every three women. However, most people feel uncomfortable to discuss it. Herein, we conducted a feasibility evaluation study for self-assessment approaches with a vaginal endoscope based on three-dimensional (3D) printing. The proposed endoscope has two parts: (a) rubber material used to cover it for its intended insertion, to avoid direct contact with the walls of the vagina, and (b) two types of sensors at the tip for measurements. The condition inside the vagina was observed with a camera and depth sensors based on the regulation of the amount of air. Arbitrary temporary prolapses from the testbed’s generator enabled us to perceive the location of the problem and symptoms that were regarded as the early stage. As discussed, the low-cost design of the 3D-printed-based vaginal endoscope provides a self-check capability and allows continuous observations that help prevent POP.

scholarly journals Left apicoposterior segmentectomy for lung cancer with displaced segmental bronchus: a case report

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Masahiro Yanagiya ◽  
Hirokazu Yamaguchi ◽  
Noriko Hiyama ◽  
Jun Matsumoto
Keyword(s):  
Lung Cancer ◽  
Indocyanine Green ◽  
Early Stage ◽  
Main Pulmonary Artery ◽  
Three Dimensional ◽  
Early Stage Lung Cancer ◽  
Case Presentation ◽  
Segmental Bronchus ◽  
Dimensional Reconstruction ◽  
Preoperative Image

Abstract Background Pulmonary segmentectomy can be challenging when thoracic surgeons encounter anatomical anomalies. A displaced left apicoposterior bronchus is a rare bronchial anomaly that makes lung anatomical resection challenging. We herein present a case of successful left apicoposterior segmentectomy for lung cancer in a patient with an anomalous segmental bronchus. Case presentation A 70-year-old man was clinically diagnosed with early-stage lung cancer for which segmentectomy was indicated. A preoperative image revealed a displaced left apicoposterior bronchus that branched behind the left main pulmonary artery. With the aid of three-dimensional reconstruction imaging and systemic indocyanine green injection, we successfully performed left apicoposterior segmentectomy under complete video-assisted thoracic surgery. The pathological diagnosis was adenocarcinoma. The patient was alive without recurrence 8 months after segmentectomy. Conclusion Preoperative three-dimensional imaging and systemic indocyanine green injection enabled us to successfully conduct challenging segmentectomy in a patient with an anomalous bronchus.

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