Triple Knots Research Articles

Nonparaxial solitons and their interaction dynamics in coupled nonlinear Helmholtz systems

It is well-known that the nonparaxiality plays an important role in the fabrication of nanoscale devices. In this paper, we study the existence of nonparaxial solitons in a dimensionless coupled nonlinear Schrödinger system with cross-phase modulation (XPM), which enables the propagation of ultra-broad nonparaxial pulses in a birefringent optical waveguide. Despite the fact that the system is a nonintegrable one (Tamilselvan et al., 2020), we obtain a bright soliton solution analytically by employing the standard Hirota’s bilinearization method. Subsequently we numerically investigate the scattering dynamics of two and three bright solitary waves using the general solution as the seed one by adopting the split-step Fourier method based on the Feit-Flock algorithm. We explain how the soliton parameters such as separation distance and relative phase influence the interaction between the nonparaxial bright solitons. In particular, we report a bunch of interesting phenomena of soliton interactions, which include oscillating bound solitons when the phase of the two solitary waves are equal and parallel propagation as the phase is changed to out-of phase with a zig-zag pattern. Similarly the in-phase three solitary waves also exhibit a novel interaction which mimics a triple knot structure which has never been observed before in the framework of coupled nonlinear Helmholtz systems. We believe that our results would pave a way for future research generating optical memories based on the nonparaxial solitons.

O-ring-induced transverse aortic constriction (OTAC) is a new simple method to develop cardiac hypertrophy and heart failure in mice

Suture-based transverse aortic constriction (TAC) in mice is one of the most frequently used experimental models for cardiac pressure overload-induced heart failure. However, the incidence of heart failure in the conventional TAC depends on the operator’s skill. To optimize and simplify this method, we proposed O-ring-induced transverse aortic constriction (OTAC) in mice. C57BL/6J mice were subjected to OTAC, in which an o-ring was applied to the transverse aorta (between the brachiocephalic artery and the left common carotid artery) and tied with a triple knot. We used different inner diameters of o-rings were 0.50 and 0.45 mm. Pressure overload by OTAC promoted left ventricular (LV) hypertrophy. OTAC also increased lung weight, indicating severe pulmonary congestion. Echocardiographic findings revealed that both OTAC groups developed LV hypertrophy within one week after the procedure and gradually reduced LV fractional shortening. In addition, significant elevations in gene expression related to heart failure, LV hypertrophy, and LV fibrosis were observed in the LV of OTAC mice. We demonstrated the OTAC method, which is a simple and effective cardiac pressure overload method in mice. This method will efficiently help us understand heart failure (HF) mechanisms with reduced LV ejection fraction (HFrEF) and cardiac hypertrophy.

Large-Scale Spinning Approach to Engineering Knittable Hydrogel Fiber for Soft Robots.

Efforts to impart responsiveness to environmental stimuli in artificial hydrogel fibers are crucial to intelligent, shape-memory electronics and weavable soft robots. However, owing to the vulnerable mechanical property, poor processability, and the dearth of scalable assembly protocols, such functional hydrogel fibers are still far from practical usage. Herein, we demonstrate an approach toward the continuous fabrication of an electro-responsive hydrogel fiber by using the self-lubricated spinning (SLS) strategy. The polyelectrolyte inside the hydrogel fiber endows it with a fast electro-response property. After solvent exchange with triethylene glycol (TEG), the maximum tensile strength of the hydrogel fiber increases from 114 kPa to 5.6 MPa, far superior to those hydrogel fiber-based actuators reported previously. Consequently, the flexible and mechanical stable hydrogel fiber is knitted into various complex geometries on demand such as a crochet flower, triple knot, thread tube, pentagram, and hollow cage. Additionally, the electrochemical-responsive ionic hydrogel fiber is capable of acting as soft robots underwater to mimic biological motions, such as Mobula-like flapping, jellyfish-mimicking grabbing, sea worm-mimicking multi-degree of freedom movements, and human finger-like smart gesturing. This work not only demonstrates an example for the large-scale production of previous infeasible hydrogel fibers, but also provides a solution for the rational design and fabrication of hydrogel woven intelligent devices.

Is two-port laparoendoscopic single-site surgery (T-LESS) feasible for pediatric hydroceles? Single-center experience with the initial 59 cases

Although T-LESS is increasingly being used to treat pediatric inguinal hernia, there is no study regarding T-LESS for pediatric hydrocele. To further evaluate the feasibility of T-LESS and present our single-center experience for repair of pediatric hydroceles. From January 2016 to July 2016, all boys undergoing T-LESS for hydrocele in our institute were retrospectively reviewed. A laparoscope and a needle-holding forceps were introduced at umbilicus. A round needle with silk suture was stabbed through the abdominal wall. The peritoneum around the internal ring was sutured continuously in a clockwise direction. After a complete purse-string suture, a triple knot was performed by using a single-instrument tie technique. The contralateral patent processus vaginalis (PPV) was repaired simultaneously if present. Overall, 59 boys with hydrocele were included (22 on the left side, 32 on the right side, and 5 bilaterally) (Table). During the procedure, all hydroceles were observed with a PPV but the fluid needed to be aspired in 39 boys. A contralateral PPV was present in 24 boys with unilateral hydrocele, and finally 88 repairs were performed. Mean operative time was 18.3min for unilateral repair and 27.5min for bilateral repair, respectively. All procedures were uneventful besides a minor injury to the inferior epigastric vessels. After a mean follow-up of 10.7 months, neither recurrence nor other postoperative complication was observed. There were no visible scars on the abdominal wall. Compared with open repair of pediatric inguinal hernia and hydrocele, laparoscopic surgery had several advantages, such as exploration of contralateral PPV, identification of rare hernias, diminished postoperative pain, improved cosmesis, faster recovery, and fewer complications. Differing from the laparoscopic retroperitoneal approach, T-LESS included no subcutaneous tissue in the ligature, and its knot was completely in the peritoneal cavity which could radically prevent the severe pain and suture granuloma in the ligated region. Furthermore, the skin incisions after T-LESS were hidden in umbilicus, which could achieve an excellent cosmetic result. By performing T-LESS for pediatric hydroceles, the current study showed very satisfactory results, such as high success rate, minor complication, and excellent cosmesis. However, because of the difficult learning curve of T-LESS, some technical details (e.g. avoiding injury to the spermatic cord, completely suturing the peritoneal folds and reducing disturbance between the instruments) still need to be improved in the future. T-LESS appears to be a safe and effective method for repair of pediatric hydroceles.

Local modification of Pythagorean-hodograph quintic spline curves using the B-spline form

The problems of determining the B–spline form of a C 2 Pythagorean–hodograph (PH) quintic spline curve interpolating given points, and of using this form to make local modifications, are addressed. To achieve the correct order of continuity, a quintic B–spline basis constructed on a knot sequence in which each (interior) knot is of multiplicity 3 is required. C 2 quintic bases on uniform triple knots are constructed for both open and closed C 2 curves, and are used to derive simple explicit formulae for the B–spline control points of C 2 PH quintic spline curves. These B-spline control points are verified, and generalized to the case of non–uniform knots, by applying a knot removal scheme to the Bézier control points of the individual PH quintic spline segments, associated with a set of six–fold knots. Based on the B–spline form, a scheme for the local modification of planar PH quintic splines, in response to a control point displacement, is proposed. Only two contiguous spline segments are modified, but to preserve the PH nature of the modified segments, the continuity between modified and unmodified segments must be relaxed from C 2 to C 1. A number of computed examples are presented, to compare the shape quality of PH quintic and “ordinary” cubic splines subject to control point modifications.

Non-uniform interpolatory curve subdivision with edge parameters built upon compactly supported fundamental splines

In this paper we present a family of Non-Uniform Local Interpolatory (NULI) subdivision schemes, derived from compactly supported interpolatory fundamental splines with non-uniform knots (NULIFS). For this spline family, the knot-partition is defined by a sequence of break points and by one additional knot, arbitrarily placed along each knot-interval. The resulting refinement algorithms are linear and turn out to contain a set of edge parameters that, when fixed to a value in the range [0,1], allow us to achieve special shape features by simply moving each auxiliary knot between the break points. Among all the members of this new family of schemes, we will then especially analyze the NULI 4-point refinement. This subdivision scheme has all the fundamental features of the quadratic fundamental spline basis it is originated from, namely compact support, C1 smoothness, second order polynomials reproduction and approximation order 3. In addition the NULI 4-point subdivision algorithm has the possibility of setting consecutive edge parameters to simulate double and triple knots—that are not considered by the authors of the corresponding spline basis—thus allowing for limit curves with crease vertices, without using an ad hoc mask. Numerical examples and comparisons with other methods will be given to the aim of illustrating the performance of the NULI 4-point scheme in the case of highly non-uniform initial data.

Treatment of massive rotator-cuff tears with a polyester ligament (Dacron) augmentation

We describe the clinical outcome of a technique of surgical augmentation of chronic massive tears of the rotator cuff using a polyester ligament (Dacron) in 21 symptomatic patients (14 men, seven women) with a mean age of 66.5 years (55.0 to 85.0). All patients had MRI and arthroscopic evidence of chronic massive tears. The clinical outcome was assessed using the Constant and Murley and patient satisfaction scores at a mean follow-up of 36 months (30 to 46). The polyester ligament (500 mm × 10 mm) was passed into the joint via the portal of Neviaser, medial to the tear through healthy cuff. The two ends of the ligament holding the cuff were passed through tunnels made in the proximal humerus at the footprint of the insertion of the cuff. The ligament was tied with a triple knot over the humeral cortex. All the patients remained free from pain (p < 0.001) with improvement in function (p < 0.001) and range of movement (p < 0.001). The mean pre-operative and post-operative Constant scores were 46.7 (39.0 to 61.0) and 85.4 (52.0 to 96.0), respectively (p < 0.001). The mean patient satisfaction score was 90%. There were two failures, one due to a ruptured ligament after one year and the other due to deep-seated infection. The MR scan at the final follow-up confirmed intact and thickened bands in 15 of 17 patients. This technique of augmentation gives consistent relief from pain with improved shoulder movement in patients with symptomatic massive tears of the rotator cuff.

Needle Colposuspension: Survey of Techniques and New Procedure Report

To treat stress urinary incontinence plenty of techniques are today available. We present the results of a new, simple and cost free technique. The finger of the surgeon in the vagina checks Cooper ligament and guides the needle to pass behind it. Then it reaches the vagina where it takes a double suture. The needle rises up with the suture just above the ligament and crossing it, returns with the double suture in the vagina. With a large triple knot a tension free suspension is obtained. The success rate of 75 % was reported. The procedure basis its effectiveness on the ability of the new structure made up around the sutures by a fibrosis, to create a tension free suspension of vagina to Cooper ligament. This technique for the treatment of incontinence is reliable, simple and cheap and without controindications.

Slipknot for scleral fixation of intraocular lenses

We describe a simple, quick technique to construct a slipknot that can be snared around the haptic of an intraocular lens (IOL) during transscleral fixation of a posterior chamber IOL or repositioning of a dislocated IOL. An in vitro experiment showed that the time required for the slipknot method was significantly less than that for the traditional triple-knot method. An additional advantage is that the slipknot technique can be performed by a single surgeon using standard ophthalmic instrumentation. In addition, the slipknot is as secure as a triple knot.

Severe intrauterine growth retardation due to taut triple knots of the umbilical cord

Severe intrauterine growth retardation due to taut triple knots of the umbilical cord

Prenatal observation of umbilical cord abnormalities: A triple knot and torsion of the umbilical cord

Umbilical cord abnormalities can be observed with ultrasonography. Two cases are described where a triple knot and torsion of the umbilical cord are observed. These cases allow the elucidation of the mechanics of formation of a triknot and torsion abnormality.

Triple knotting of a central venous catheter

A case of unusual triple knotting of a central venous catheter inserted through the left basilic vein is reported. The catheter with intact triple knots could be withdrawn without an invasive maneuver. A possible cause of triple knotting was discussed in regard to the anatomic configuration of the central veins. This case emphasizes that a central venous catheter should not be advanced if resistance is encountered.