Single Wedge Research Articles

Early Paleozoic suprasubduction complexes of the North Balkhash ophiolite zone (Central Kazakhstan): Geochronology, geochemistry and implications for tectonic evolution of the Junggar-Balkhash Ocean

The Junggar-Balkhash region in the west of the Central Asian orogenic belt (САОВ) comprises Paleozoic flysch, dismembered ophiolites, cherts, basalts, and olistostromes within its accretionary wedges. The North Balkhash ophiolite zone hosts serpentinite mélange with slivers of early Paleozoic chert, basalt, tuffaceous chert and volcaniclastic rocks. For the first time in the North Balkhash ophiolite zone, we recognized the Cambrian to Early and Middle Ordovician supra-subduction complexes in the plutonic fragments along with the previously known Middle to Late Ordovician OIB, N-MORB, chert and Late Ordovician island arc volcanic slivers.The documented records of North Balkhash supra-subduction complexes therefore span 100 m.y.-long evolution of the early Paleozoic intraoceanic accretionary wedge that went through several reorganizations due to incorporation of oceanic island and oceanic floor units in its front.The Early Cambrian is represented by Tesiktas ultramafic-gabbro-plagiogranite (c. 530 Ma) and Eastern Arkharsu gabbro-dolerite-plagiogranite (520 ± 2 Ma) with boninitic signature, interpreted to have formed in fore-arc setting. The Late Cambrian (498 ± 8 Ma) and Early Ordovician (476 ± 3 Ma) rocks are represented by island arc plagiogranite and diorite blocks in serpentinite melange along with slivers of Middle Ordovician dacite and andesite with lenses of chert rocks, as well as tuff and tuffaceous sandstone.Correlation of the North-Balkhash zone with its possible equivalents in Kazakhstan and NW China revealed the same duration, stages and tectonic settings. Particularly, we propose that the North Balkhash and West Junggar ophiolite melanges can be considered as fragments of the formerly single subduction-accretionary wedge, dextrally displaced for 250 km along the Junggar strike-slip fault during the late Paleozoic to the early Mesozoic.

Testing large convex aspheres using a single wedge compensation and stitching method

Testing large convex aspheric mirrors has always been a challenging metrology problem in optics. In response to this problem, a modified method that utilizes single wedge compensation to measure large convex aspheric mirrors is proposed in this paper. The principles of this method and aberration theory are first analyzed. Two simulation examples are designed to verify the method’s applicability, and the sensitivity of this configuration is also analyzed, which proves that the accuracy of the configuration can be better than 0.006 λ (3.8 nm) with careful alignment and calibration. These examples and this analysis show that this configuration is feasible and flexible.

Short single-wedge stems have higher risk of periprosthetic fracture than other cementless stem designs in Dorr type A femurs: a finite element analysis.

The use of total hip arthroplasty (THA) femoral stems that transmit force in a favourable manner to the femur may minimise periprosthetic fractures. Finite element analysis (FEA) is a computerised method that analyses the effect of forces applied to a structure with complex shape. Our aim was to apply FEA to compare primary THA cementless stem designs and their association with periprosthetic fracture risk. 3-dimensional (3D) models of a Dorr Type A femur and 5 commonly used primary THA cementless stem designs (short single wedge, standard-length single wedge, modular, double-wedge metaphyseal filling, and cylindrical fully coated) were developed using computed tomography (CT) imaging. Implant insertion, single-leg stance, and twisting with a planted foot were simulated. FEA was performed, and maximum femoral strain along the implant-bone interface recorded. Femoral strain was highest with short single-wedge stem design (0.3850) and lowest with standard-length single-wedge design (0.0520). Location of maximum femoral strain varied by stem design, but not with implant insertion, single-leg stance, or twisting with a planted foot. Strain was as high during implant insertion as with single-leg stance or twisting with a planted foot. Our results suggest the risk of intraoperative and postoperative periprosthetic fracture with THA in a Dorr A femur is highest with short single-wedge stems and lowest with standard-length single-wedge stems. Consideration may be given to minimising the use of short single-wedge stems in THA. Implant-specific sites of highest strain should be carefully inspected for fracture.

Relative contributions of large-scale and wedgelet currents in the substorm current wedge

We examined how much large-scale and localized upward and downward currents contribute to the substorm current wedge (SCW), and how they evolve over time, using the THEMIS all-sky imagers (ASIs) and ground magnetometers. One type of events is dominated by a single large-scale wedge, with upward currents over the surge and broad downward currents poleward-eastward of the surge. The other type of events is a composite of large-scale wedge and wedgelets associated with streamers, with each wedgelet having comparable intensity to the large-scale wedge currents. Among 17 auroral substorms with wide ASI coverage, the composite current type is more frequent than the single large-scale wedge type. The dawn–dusk size of each wedgelet is ~ 600 km in the ionosphere (~ 3.2 RE in the magnetotail, comparable to the flow channel size). We suggest that substorms have more than one type of SCW, and the composite current type is more frequent.

Selective Generation of Lamb Wave Modes in a Finite-Width Plate by Angle-Beam Excitation Method.

A Lamb wave in a plate with a finite width has both thickness and width modes, whereas only thickness modes exist in an infinitely wide plate. The thickness and width modes are numerously formed in a finite-width plate, and they all have different cut-off frequencies, wave velocities, and wave structures. These different characteristics can be utilized in various applications, but a selective generation method for a particular Lamb wave mode in a finite-width plate has not been sufficiently studied, and only a method using multiple elements has been reported. This paper presents the selective generation of a certain Lamb wave mode in a finite-width plate by an angle-beam excitation method using single or dual wedges. In the proposed generation method, a specially designed wedge with grooves or a patch having insulation layers is employed for partial acoustic insulation of the ultrasonic energy incident into the plate. The feasibility of the proposed method was investigated through finite element method (FEM) simulations for Lamb wave excitation and propagation, and then experimentally demonstrated by the measurement of Lamb wave propagation using a laser scanning vibrometer.

Postoperative atrial fibrillation prophylaxis using a novel amiodarone order set.

BackgroundStudies have demonstrated that chemoprophylaxis following anatomic lung resection can reduce post-operative atrial fibrillation (POAF). However, it is unclear if non-anatomic wedge resection warrants prophylaxis, as previously published rates vary widely. The primary goal of this study was to assess an institutional rate of POAF following anatomic resections with implementation of a novel amiodarone administration regimen compared to wedge resections without prophylaxis.MethodsWe performed a retrospective cohort study of a prospectively maintained database and compared anatomic and wedge lung resection patients from 1/2015 to 4/2018. During the study period, a previously unpublished amiodarone order set consisting of a 300 mg IV bolus followed by 400 mg tablets TID ×3 days was administered to anatomic resection patients ≥65 who met criteria. Wedge resection patients were not intended to receive amiodarone prophylaxis. The primary outcome was POAF incidence. Risk factors for developing POAF were assessed.ResultsA total of 537 patients met inclusion where 56% underwent anatomic resection and 44% wedge resection. Overall, 5.4% of patients experienced POAF. There was a significant reduction in post-anatomic resection POAF as compared to historic rates without prophylaxis (9.3% vs. 20.3%, P<0.001). A single wedge resection patient (0.4%) developed POAF. On multivariable analysis, the only independent POAF risk factor was age ≥65 (OR: 5.41, 95% CI: 1.47–19.85).ConclusionsAdministration of our novel amiodarone order set reduces POAF after anatomic resection; however, POAF following wedge resection is too rare to warrant chemoprophylaxis.

Classifications in Brief: The Dorr Classification of Femoral Bone.

Classifications in Brief: The Dorr Classification of Femoral Bone.

Combined Anterior Cruciate Ligament Reconstruction and High Tibial Osteotomy in Anterior Cruciate Ligament-Deficient Varus Knees

Background: The presence of varus deformity in anterior cruciate ligament (ACL)-deficient knees can be a source of persistent knee pain owing to medial compartment overload. This deformity may threaten the outcome of ACL reconstruction because of increased tension on the graft. Methods: In the period between May 2018 to september 2019, short term pilot study including 10 patients with ACL deficiency and genu varus were treated by anatomical single bundle ACL reconstruction and open medial wedge high tibial osteotomy in same sitting. The selected patients had manifestations of ACL deficiency in association with medial joint line pain with or without lateral thrust. Prospective evaluation using the international knee documentation committee (IKDC) score was performed. The mean follow-up period was 6 months. Results: This technique achieved knee stability and realignment to normal values. The IKDC score significantly improved from 37 preoperative to 78 postoperative (p < 0.05). Conclusion: The combined procedure of ACL reconstruction and high tibial osteotomy restored knee stability and reduced pain over the medial compartment. Although the combined procedure has a longer period of rehabilitation than an isolated ACL reconstruction, the elimination of lateral thrust and preservation of articular cartilage of the medial compartment are of paramount importance to the future of these knees.

Surgical outcome with single stage procedure for neglected congenital talipes equinovarus

&lt;p class="abstract"&gt;&lt;strong&gt;Background:&lt;/strong&gt; Congenital talipes equinovarus is one of the commonest congenital anomalies. In developing countries like India especially in the rural population still there are many myths, culture and awareness issues regarding this deformity. Many patients get initial treatment with casting but tend loose follow ups in this prolonged treatment. To give optimal results in these scenarios, the technique for single stage procedure which includes bony and soft tissue repair gives excellent results.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Methods:&lt;/strong&gt; In a retrospective longitudinal study, 13 children with neglected clubfeet were involved. Valid consent, clinical and radiological evaluation was done. Patients underwent single stage (bony and soft tissue) procedure described in the study. Post operatively data was collected and scoring was done as per International clubfoot study group (ICSG) at each follow ups.&lt;strong&gt;&lt;/strong&gt;&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Results:&lt;/strong&gt; A total 13 children out of whom 9 were male and 4 females, all having unilateral deformity were studied. The age group was between 5-22 years (mean 13.5). Postoperatively, the children were followed at 6 months intervals. As per ICSG score 10 patients had excellent results, 3 patients had good results and none had poor results. 2 patients had minor complication - delayed wound healing (2-3 weeks).&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Conclusions:&lt;/strong&gt; Treatment of neglected clubfoot using single stage procedure dorsal close wedge osteotomy with soft tissue release has a high rate of good and excellent results, with low frequency of complications. It is a good alternative to conventional procedures for management of neglected clubfeet in developing countries, where compliance of patient is a problem.&lt;/p&gt;

Experimental study on water entry of twin wedges

This article presents an experimental study on the water entry of twin wedges commonly used as sections of catamaran craft. A twin wedge is a combination of two single asymmetry wedges connected by so-called wet-deck. The single asymmetry wedge has a vertical side and a non-vertical side with a range of deadrise angles. This study is carried out on a set of twin wedges of 7°, 15° and 20° deadrise angles. For calibrating the experimental equipment, the twin wedges symmetric quality, tank depth effect, three-dimensional effect, repeatability and sampling rate effects are examined. The water entry experiments are conducted through a drop test method. Time histories of impact pressure are recorded for different deadrise angles, drop heights and space between two single wedges. The results show that the effect of space on the peak pressure is negligible. In water entry experiment, the pressure on the non-vertical side of an asymmetry wedge is considerably lower than that on the equivalent symmetry wedge. The vertical side of an asymmetry wedge is under the effect of air entrapment. It has much less pressure than the non-vertical side.

Treatment of a combined deformity following tibial tubercle ventromedialization with single proximal tibial closing wedge osteotomy

Patellar instability in skeletally immature patients must be approached with concern of potential damage to physes. In this article, we present a case of combined knee deformity consisting of genu recurvatum, genu valgum and patella baja which arose subsequent to a pediatric tibial tubercle ventromedialization. Patient was a female who was 22 years old upon first admission. After confirming cartilage to be in good health, the deformity was corrected with a single supratubercular posteriorly and medially based proximal tibial closing wedge osteotomy. At the seventh year follow-up, patient was pain free, functionally satisfied and radiographic evaluation showed correct alignment. This case illustrates the consequent difficulties faced if physeal damage occurs during treatment of patellar instability as well as effectiveness of a single well-planned supratubercular proximal tibial osteotomy treating combined genu recurvatum, genu valgum and patella baja deformities; although anatomic and clinical studies are required to generalize its use.

Free Energy Landscape of Colloidal Clusters in Spherical Confinement.

The structure of finite self-assembling systems depends sensitively on the number of constituent building blocks. Recently, it was demonstrated that hard sphere-like colloidal particles show a magic number effect when confined in emulsion droplets. Geometric construction rules permit a few dozen magic numbers that correspond to a discrete series of completely filled concentric icosahedral shells. Here, we investigate the free energy landscape of these colloidal clusters as a function of the number of their constituent building blocks for system sizes up to several thousand particles. We find that minima in the free energy landscape, arising from the presence of filled, concentric shells, are significantly broadened, compared to their atomic analogues. Colloidal clusters in spherical confinement can flexibly accommodate excess particles by ordering icosahedrally in the cluster center while changing the structure near the cluster surface. In between these magic number regions, the building blocks cannot arrange into filled shells. Instead, we observe that defects accumulate in a single wedge and therefore only affect a few tetrahedral grains of the cluster. We predict the existence of this wedge by simulation and confirm its presence in experiment using electron tomography. The introduction of the wedge minimizes the free energy penalty by confining defects to small regions within the cluster. In addition, the remaining ordered tetrahedral grains can relax internal strain by breaking icosahedral symmetry. Our findings demonstrate how multiple defect mechanisms collude to form the complex free energy landscape of colloidal clusters.

Comparison of dose calculation algorithms model: Convolution, superposition, and fast superposition in 3-D Conformal Radiotherapy (3D-CRT) treatment plan

The important task of radiotherapy is to make sure that the radiation dose to the target tumour is accurate as prescribed and the dose to the organ at risk is minimized. Therefore, the aim of this study is to compare and evaluate the efficiency of the dose calculation algorithms: namely convolution, superposition, and fast superposition which installed in Treatment Planning System (TPS) (CMS XiO, USA). In this study, we modified protocols described in IAEATecdoc-1583, where four typical treatment techniques such as single field, multiple field, wedge field, and multi-leaf collimated (MLC) field were analysed from the system. The measurement data for calculated dose and measured dose were taken from thorax CIRS anthropomorphic phantom. The assessment of algorithms was done by comparing the point dose calculated with the measured dose. The study shows that the superposition algorithm produced relative error less than ± 3% which passed 100% of all reference points, whilst the convolution algorithm and fast superposition presented relative error more than ± 3% which passed 82% and 91% of reference points, respectively. In conclusion, the evaluation of radiotherapy treatment plan shall take into account the type of dose calculation algorithm model in order to optimize radiotherapy treatment and ensure the radiation safety to the patient.

Numerical Analysis of Influence of Roughness of Material Surface on High-Speed Liquid Droplet Impingement

This study explains why the deep erosion pits are formed in liquid droplet impingement erosion even though the droplets uniformly impinge on the entire material surface. Liquid droplet impingement erosion occurs in fluid machinery on which droplets impinge at high speed. In the process of erosion, the material surface becomes completely roughened by erosion pits. In addition, most material surface is not completely smooth and has some degree of initial roughness from manufacturing and processing and so on. In this study, to consider the influence of the roughness on the material surface under droplet impingement, a numerical analysis of droplets impinging on the material surface with a single wedge and a single bump was conducted with changing offsets between the droplet impingement centers and the roughness centers on each a wedge bottom and a bump top. As results, two mechanisms are predicted from the present numerical results: the erosion rate accelerates and transitions from the incubation stage to the acceleration stage once roughness occurs on the material surface; the other is that deep erosion pits are formed even in the case of liquid droplets impinging uniformly on the entire material surface.

Water entry of a finite width wedge near a floating body

The problem of a two-dimensional finite-width wedge entering water near a freely floating body is considered through the velocity potential theory for the incompressible liquid with the fully nonlinear boundary conditions on the free surface. The problem is solved by using the boundary element method in the time domain. The numerical process is divided into two phases based on whether the interaction between the wedge and floating body is significant. In the first phase, when the single wedge enters water at initial stage, only a small part near its tip is in the fluid, the problem is studied in a stretched coordinate system and the presence of the floating body has no major effect. In the second phase, the disturbance by water entry of the wedge has reached the floating body, and both are considered together in the physical system. The auxiliary function method is adopted to decouple the nonlinear mutual dependence between the motions of the wedge and floating body, both in three degrees of freedom, and the fluid flow, as well as the interaction effects between them. Case studies are undertaken for a wedge entering water in forced or free fall motion, vertically or obliquely. Results are provided for the accelerations, velocities, pressure distribution and free surface deformation, and the interaction effects are discussed.

Laparoscopic liver resection: evolution of a single Surgeon's experience in MILS with 129 cases

Background: Interest in MILS is increasing,showing significant postoperative advantages for patients Methods: A single Surgeon with advanced expertise in both open HBP surgery as well as in advanced laparoscopic GI surgery,started a development program for introducing MILS at a large tertiary referral institution in northern Italy, in 2006.In 10 years activity 129 patients underwent laparoscopic liver resection. Results: Preoperative diagnosis was CLM in 33,5%, HCC in 15.5%, IHCC+CCC in 7%, Non-Colorectal Liver Metastases in 2%,Benign Lesions in 42%.Median operation time was 154 min.Transfusion were necessary in 10%. Liver-specific conversion rate 18.6%. Most common procedures were Single wedge(29.5%), Segmentectomy(16.3%), Left lateral sectionectomy(21.7%).Major complication (Clavien-Dindo>= 3) rate was 10% and median LOS was 5 days.Mortality occurred in none. Conclusion: TECHNICAL TIPS& RICKS (Educational Video):Intraoperative ultrasound was performed to confirm the number and location of hepatic lesions as well as their proximity to portal pedicles and hepatic veins. Liver parenchyma was transected using ultrasonic scalpel with need of #2 Pringle maneuvers (duration 20 min each-20 min off). Parenchymal transection with ultrasonic scalpel was undertaken following the US-guided demarcation line. Branches of bile ducts, portal and hepatic veins,were controlled by Hem-o-lok clips or single stitches. Trisegmentectomy (IVbs-Vs-VIs) was performed.Patients are managed post-operatively according to ERAS institutional protocol

Analytic inverse solutions for Risley prisms in four different configurations for positing and tracking systems.

The conventional ray deviation formula and analytical inverse solution for Risley prisms are traditionally derived by the first-order paraxial method, which is simplified and does not provide sufficient accuracy. When a light ray enters the wedge prism, the component that is perpendicular to the base side is deviated by the wedge prism and the component parallel to the base side is uninfluenced. In this study, the problem is presented and analyzed from the scalar form of Snell's law, and 2D vector algebra is used to solve the problem. The rotation and refracting angles of a single wedge prism are obtained by analyzing the propagation through the prism of incident rays from different directions, and ray deviation formulas are derived. Four configurations are described with ray deviation formulas and analytical inverse solutions deduced from the corresponding formulas for a single wedge prism. In the final section, two examples are considered for the four configurations. The numeric results demonstrate the accuracy of the inverse solution provided by the proposed method.

Determination of an Effective Wedge Angle by Combination of Two Arbitrary Universal Wedge Fields in Radiation Therapy of Cancer Patients with Megavoltage Photon Beams.

Introduction: Wedge filters are commonly used in radiation oncology for eliminating hot spots and creating a uniform dose distribution in optimizing isodose curves in the target volume for clinical aspects. These are some limited standard physical wedges (15°, 30°, 45°, 60°), or creating an arbitrary wedge angle, like motorized wedge or dynamic wedge, ... The new formulation is presented by the combination of wedge fields for determining an arbitrary effective wedge angle. The isodose curves also are derived for these wedges. Materials and Methods: we performed the dosimetry of Varian Clinac 2100C/D with Scanditronix Wellhofer water blue phantom, CU500E, OmniPro - Accept software and 0.13cc ionization chamber for 6Mv photon beam in depth of 10cm (reference depth) for universal physical wedges (15°, 30°, 45°, and 60°) and reference field 10x10cm2. By combining the isodose curve standard wedge fields with compatible weighting dose for each field, the effective isodose curve is calculated for any wedge angle. Results: The relation between a given effective wedge angle and the weighting of each combining wedge fields was derived. A good agreement was found between the measured and calculated wedge angles and the maximum deviation did not exceed 3°. The difference between the measured and calculated data decreased when the combined wedge angles were closer. The results are in agreement with the motorized single wedge appliance in the literature. Conclusion: This technique showed that the effective wedge angle that is obtained from this method is adequate for clinical applications and the motorized wedge formalism is a special case of this consideration.

Composite wavelength tunable wedged interference structures with increased free spectral range

In the present paper, we propose a compact composite wedge interference structure by combining wedges with different geometry. We use interferential wedges with optical thickness from several micrometers to several hundred micrometers and apex angles of the order of tens microradians. The aim of the conducted study is to prove that such a structure exhibits improved optical properties in comparison to a conventional wedge. We have carried out simulations and experiments with a structure built from two wedges. We have shown that, instead of multiple transmission peaks observed for a single interferential wedge, the composite structure provides selection of a single resonance in transmission within the impact area of a large diameter monochromatic beam and enables wavelength tuning when a small diameter multi-wavelength beam is used. The first property ensures analysis of light beams characterized with a wide spectrum. The second feature allows for increase of the wavelegth tuning range at keeping spectrally narrow transmission peak if the structure is formed by a thin and a thick interferential wedges. Two such structures have been realized using a technique which we have developed. The experiments made with this structures show that the produced transmission peak is narrowed spatially and spectrally at the expense of lower transmission which achieves 50–60% of transmission ensured by the used interferential wedges.

Minor laparoscopic liver resection as day-case surgery (without overnight hospitalization): a pilot study

Introduction: Day-case surgery (DCS) has boomed over recent years, as has laparoscopic liver resection (LLR) for the treatment of liver tumor (benign or malign). The purpose of this prospective study was to show the feasibility of minor LLR as DCS. Material and methods: This was a prospective, intention to treat, non-randomized study of consecutive patients undergoing minor LLR from July 2015 to December 2017. Exclusion criteria were liver resection using laparotomy, major LLR, difficult locations for minor LLR, major abdominal surgery using laparotomy, hepatobiliary procedures without liver parenchyma resection, cirrhosis with Child >A and/or portal hypertension, presence of a significant medical history and exclusion criteria for DCS. Primary endpoint was the unplanned overnight admission rate. Secondary endpoints were criteria for DCS evaluation, satisfaction and compliance to the protocol. Results: During the study period, 167 patients underwent liver resection. On this population, 23 (25%) were included as DCS. Causes for minor LLR were liver metastasis (n=9), hepatic adenoma (n=5), hepatocellular carcinoma (n=4), ciliated hepatic foregut cyst (n=2) and other benign tumors (n=3). All day-case minor LLR excepted two patients consisted of single wedge resection and one patient had left lateral sectionectomy. There were four unplanned overnight admissions (17.4%). There were one unexpected consultations (4.3%), two hospital readmissions (8.6%) and no major complications or mortality. Compliance to the protocol was 69.5%. Satisfaction rate was 91%. Conclusion: In selected patients, day-case minor LLR is feasible and has acceptable complication and readmission rates. Hence, day-case minor LLR can be legitimately implemented for selected patients.