14 research outputs found
Solitary waves of the two-dimensional Camassa-Holm - Nonlinear Schrödinger equation
In this work, we study solitary waves in a (2 + 1)-dimensional variant of the defocusing nonlinear Schr dinger (NLS) equation, the so-called Camassa-Holm-NLS (CH-NLS) equation. We use asymptotic multiscale expansion methods to reduce this model to a Kadomtsev Petviashvili (KP) equation. The KP model includes both the KP-I and KP-II versions, which possess line and lump soliton solutions. Using KP solitons, we construct approximate solitary wave solutions on top of the stable continuous-wave solution of the original CH-NLS model, which are found to be of both the dark and antidark type. We also use direct numerical simulations to investigate the validity of the approximate solutions, study their evolution, as well as their head-on collisions. © 2018 IOP Publishing Ltd
Direct perturbation theory for dark-bright solitons: Application to Bose-Einstein condensates
We develop a direct perturbation theory for dark-bright solitons and derive evolution equations for the soliton parameters. In particular, first the linearization equation around the solitons is solved by expanding its solution into a set of complete eigenfunctions of the linearization operator. Then, suppression of secular growth in the linearized solution leads to the evolution equations of soliton parameters. The results are applied to a number of case examples motivated by the physics of atomic Bose-Einstein condensates, where dark-bright solitons have recently been studied both in theory and in experiments. We thus consider perturbations corresponding to (a) finite temperature-induced thermal losses, and (b) the presence of localized (δ-function) impurities. In these cases, relevant equations of motion for the dark-bright soliton center are in agreement with ones previously obtained via alternative methods, including energy-based methods, as well as numerical linear stability analysis and direct simulations. © 2016 IOP Publishing Ltd
Asymptotic expansions and solitons of the Camassa–Holm – nonlinear Schrödinger equation
We study a deformation of the defocusing nonlinear Schrödinger (NLS) equation, the defocusing Camassa–Holm NLS, hereafter referred to as CH–NLS equation. We use asymptotic multiscale expansion methods to reduce this model to a Boussinesq-like equation, which is then subsequently approximated by two Korteweg–de Vries (KdV) equations for left- and right-traveling waves. We use the soliton solution of the KdV equation to construct approximate solutions of the CH–NLS system. It is shown that these solutions may have the form of either dark or antidark solitons, namely dips or humps on top of a stable continuous-wave background. We also use numerical simulations to investigate the validity of the asymptotic solutions, study their evolution, and their head-on collisions. It is shown that small-amplitude dark and antidark solitons undergo quasi-elastic collisions. © 2017 Elsevier B.V
Performing modified fontan before six years of age leads to superior long-term exercise capacity
We investigated the influence of age at Fontan completion on the exercise capacity of patients who underwent a Fontan operation. Our study demonstrated that age at the time of the Fontan operation significantly affects the peak oxygen consumption at mid-term follow up and that exercise capacity is superior in patients who have undergone Fontan completion at an earlier age. These findings provide support for recommendations to perform Fontan completion procedures relatively early. © 2020 Hellenic Society of Cardiolog
Permanent pacemaker implantation in pediatric heart transplant recipients: A systematic review and evidence quality assessment
Bradyarrhythmias are a common complication following pediatric OHT and may require permanent pacemaker implantation (PPM). The purpose of this study was to investigate the incidence, predictors, and outcomes of children undergoing PPM implantation following OHT. A PRISMA-compliant systematic literature review was performed using the PubMed database and the Cochrane Library (end-of-search date: January 27, 2019). The Newcastle-Ottawa scale and the Joanna Briggs Institute tool were used to assess the quality of cohort studies and case reports, respectively. We analyzed data from a total of 11 studies recruiting 7198 pediatric patients who underwent heart transplant. PPM implantation was performed in 1.9% (n = 137/7,198; 95% CI: 1.6-2.2) of the patients. Most patients underwent dual-chamber pacing (46%, 95% CI: 32.6-59.7). Male-to-female ratio was 1.3:1. Mean patient age at the time of OHT was 10.1 ± 6.3. Overall, biatrial anastomosis was used in 62.2% (95% CI: 52.8-70.6) of the patients. The bicaval technique was performed in the remaining 37.8% (95% CI: 29.4-47.1). Sinus node dysfunction was the most frequent indication for PPM implantation (54.4%; 95% CI: 42.6-65.7) followed by AV block (45.6%; 95% CI: 34.3-57.3). The median time interval between OHT and PPM implantation ranged from 17 days to 12.5 years. All-cause mortality was 27.9% (95% CI: 18.6-39.6) during a median follow-up of 5 years. PPM implantation is rarely required after pediatric OHT. The most common indication for pacing is sinus node dysfunction, and patients undergoing biatrial anastomosis may be more likely to require PPM. © 2020 Wiley Periodicals, Inc
Minimally Invasive Surgery vs Device Closure for Atrial Septal Defects: A Systematic Review and Meta-analysis
Device closure is the first-line treatment for most atrial septal defects (ASDs). Minimally invasive cardiac surgery (MICS) has been found safe and effective for ASD closure with comparable mortality/morbidity and superior cosmetic results compared to conventional median sternotomy. Our goal was to compare percutaneous versus MICS of ASDs. A systematic review was performed using PubMed and the Cochrane Library (end-of-search date on May 22, 2019). Meta-analyses were conducted using fixed and random effects models. In the present systematic review, we analyzed six studies including 1577 patients with ASDs who underwent either MICS (n = 642) or device closure (n = 935). Treatment efficacy was significantly higher in the MICS (99.8%; 95% CI 98.9–99.9) compared to the device closure group (97.3%; 95% CI 95.6–98.2), (OR 0.1; 95% CI 0.02–0.6). Surgical patients experienced significantly more complications (16.2%; 95% CI 13.0–19.9) compared to those that were treated with a percutaneous approach (7.1%; 95% CI 5.0–9.8), (OR 2.0; 95% CI 1.2–3.2). Surgery was associated with significantly longer length of hospital stay (5.6 ± 1.7 days) compared to device closure (1.3 ± 1.4 days), (OR 4.8; 95% CI 1.1–20.5). Residual shunts were more common with the transcatheter (3.9%; 95% CI 2.7–5.5) compared to the surgical approach (0.95%; 95% CI 0.3–2.4), (OR 0.1; 95% CI 0.06–0.5). There was no difference between the two techniques in terms of major bleeding, hematoma formation, transfusion requirements, cardiac tamponade, new-onset atrial fibrillation, permanent pacemaker placement, and reoperation rates. MICS for ASD is a safe procedure and compares favorably to transcatheter closure. Despite longer hospitalization requirements, the MICS approach is feasible irrespective of ASD anatomy and may lead to a more effective and durable repair. © 2020, Springer Science+Business Media, LLC, part of Springer Nature
IL-17E (IL-25) Enhances Innate Immune Responses during Skin Inflammation.
IL-17E (IL-25) is a member of the IL-17 cytokine family involved in the promotion of type 2 immune responses. Recently, IL-17E has been reported to be up-regulated in distinct skin inflammatory diseases such as psoriasis and atopic and contact dermatitis. We assessed the role played by IL-17E in skin inflammation. Here, we show that IL-17E induces skin inflammation in vivo, characterized by the expression of innate immune response genes and the recruitment of innate immune cells, particularly neutrophils. Genetic deletion or IL-17E neutralization ameliorated skin inflammation induced by imiquimod application or tape stripping, with reductions in neutrophil and macrophage infiltration as assessed by t-distributed stochastic neighbor embedding-guided multiparameter flow cytometry analysis, in mice. In humans, IL-17E promotes the recruitment of neutrophils via activation of macrophages in a p38-dependent mechanism. In addition, IL-17E is up-regulated in neutrophil-rich inflammatory skin diseases, such as pyoderma gangrenosum and acute generalized exanthematous pustulosis. Our data show a role for IL-17E in skin inflammation that is unrelated to the development of type 2 immune reactions. We propose that IL-17E is an important common denominator of chronic skin inflammation, promoting innate immune cell recruitment and activation
Surgical Outcomes in Syndromic Tetralogy of Fallot: A Systematic Review and Evidence Quality Assessment
Tetralogy of Fallot (ToF) is one of the most common cyanotic congenital heart defects. We sought to summarize all available data regarding the epidemiology and perioperative outcomes of syndromic ToF patients. A PRISMA-compliant systematic literature review of PubMed and Cochrane Library was performed. Twelve original studies were included. The incidence of syndromic ToF was 15.3% (n = 549/3597). The most prevalent genetic syndromes were 22q11.2 deletion (47.8%; 95% CI 43.4–52.2) and trisomy 21 (41.9%; 95% CI 37.7–46.3). Complete surgical repair was performed in 75.2% of the patients (n = 161/214; 95% CI 69.0–80.1) and staged repair in 24.8% (n = 53/214; 95 CI 19.4–30.9). Relief of RVOT obstruction was performed with transannular patch in 64.7% (n = 79/122; 95% CI 55.9–72.7) of the patients, pulmonary valve-sparing technique in 17.2% (n = 21/122; 95% CI 11.5–24.9), and RV-PA conduit in 18.0% (n = 22/122; 95% CI 12.1–25.9). Pleural effusions were the most common postoperative complications (n = 28/549; 5.1%; 95% CI 3.5–7.3). Reoperations were performed in 4.4% (n = 24/549; 95% CI 2.9–6.4) of the patients. All-cause mortality rate was 9.8% (n = 51/521; 95% CI 7.5–12.7). Genetic syndromes are seen in approximately 15% of ToF patients. Long-term survival exceeds 90%, suggesting that surgical management should be dictated by anatomy regardless of genetics. © 2019, Springer Science+Business Media, LLC, part of Springer Nature