Suppression of extreme events and chaos in a velocity-dependent potential system with time-delay feedback

The foremost aim of this study is to investigate the influence of time-delayed feedback on extreme events in a non-polynomial system with velocity dependent potential. To begin, we investigate the effect of this feedback on extreme events for four different values of the external forcing parameter. Among these four values, in the absence of time-delayed feedback, for two values, the system does not exhibit extreme events and for the other two values, the system exhibits extreme events. On the introduction of time-delayed feedback and varying the feedback strength, we found that extreme events get suppressed as well as get induced. When the feedback is positive, suppression occurs for a larger parameter region whereas in the case of negative feedback it is restricted to the limited parameter region. We confirm our results through Lyapunov exponents, probability density function of peaks, $d_{max}$ plot and two parameter probability plot. Finally, we analyze the changes in the overall dynamics of this system under the influence of time-delayed feedback. We notice that complete suppression of chaos occurs in the considered system for higher values of the time-delayed feedback.Comment: 28 pages, 16 figures, 1 table, Accepted for Publication Chaos, Solitons & Fractal

Development of material models to predict the crashworthiness of tubes

Metallic tubes have been extensively studied for their crashworthiness as they closely resemble automotive crash rails. Recently, the demand to produce light weight yet safer vehicles has led to the need to understand the behaviour of novel materials such as composites, metallic foams and sandwich structures durign a crash. This paper presents a method to predict the crashworthiness of structural components using material modes. The material factors that most affect the crushing response are determined and quantified by developing and validating the crushing of a square tube model in Abaqus. The inputs from the model are used to construct a simple, physically realistic constitutive model and new test methods for predicting the material behaviour at high strain rates using low test speeds. These material models enable a designer to predict the crash behaviour of a structure without the need to perform extensive physical tests, thus reducing the time and cost of development

A Prospective Study on the Clinical Outcomes in the Surgical Management of Failed ERCP Choledocholithiasis: An Institutional Experience

BACKGROUND: Choledocholithiasis or common bile duct stones (CBDS) may occur in up to 3%–14.7% of all patients for whom cholecystectomy is performed.1 Different methods have been used for the treatment of CBDS but the suitable therapy depends on conditions such as patient satisfaction, number and size of stones, and the surgeons experience in laparoscopy. Endoscopic retrograde cholangiopancreatography (ERCP) with or without endoscopic biliary sphincterotomy, laparoscopic CBD exploration (LCBDE - transcystic or transcholedochal), or laparotomy with CBD exploration (OCBDE by T-tube, C-tube insertion, Choledochoenterostomy or primary closure) are the most commonly used methods for managing CBDS.2 The study aims to revisit the pathophysiology and diagnosis of CBDS and compare the different techniques of treatment with a special focus on the various surgical modalities. OBJECTIVES: The study aimed to determine the clinical, radiological and biochemical characteristics of CBD stones, that make them prone to ERCP failure. Another objective was to study the clinical outcomes between the OCBDE + T and OCBDE + CDD/CDJ and LCBDE groups. MATERIALS And METHODS: The study was a prospective, observational study conducted in a tertiary care centre from March 2017 to September 2018, inducting the first 30 patients with ERCP failed choledocholithiasis. These patients (n = 30) subsequently underwent open or laparoscopic common bile duct exploration for complex biliary stone disease. The 30 patients included in the study were observed in three different treatment groups, viz. A) OC+OCBD+/-T; B) OC+OCBDE+CD/CJ/HJ; C) LC+LCBDE. RESULTS: The characteristic features of choledocholithiasis, which is prone for ERCP failure based on our study population (n = 30) are multiple (>3), large (>14 mm), proximal 1/3rd, mixed stones with CBD diameter > 14 mm. There is no difference in the clinical outcomes, radiological, and biochemical clearance of CBD stones, length of hospital stay between Open CBD Exploration with T-tube or Choledochoenterostomy and Laparoscopic CBD Exploration, except for the Quality adjusted Life years lost, which is least in laparoscopic CBE exploration patients (p < 0.001). CONCLUSION: The ideal management of choledocholithiasis remains controversial, but the treatment for choledocholithiasis must always be tailored to the needs of each patient

Involvement of Innate Immune System in Late Stages of Inherited Photoreceptor Degeneration

Retinitis pigmentosa (RP) is a group of inherited retinal degenerations that lead to progressive vision loss. Over 200 mutations in 60 different genes have been shown to cause RP. Given the diversity of genes and mutations that cause RP, corrective gene therapy approaches currently in development may prove both time-consuming and cost-prohibitive for treatment of all forms of RP. An alternative approach is to find common biological pathways that cause retinal degeneration in various forms of RP, and identify new molecular targets. With this goal, we analyzed the retinal transcriptome of two non-allelic forms of RP in dogs, rcd1 and xlpra2, at clinically relevant advanced stages of the two diseases. Both diseases showed very similar trends in changes in gene expression compared to control normal dogs. Pathway analysis revealed upregulation of various components of the innate immune system in both diseases, including inflammasome and complement pathways. Our results show that the retinal transcriptome at advanced stages of RP is very similar to that of other retinal degenerative diseases such as age-related macular degeneration and diabetic retinopathy. Thus, drugs and therapeutics already in development for targeting these retinopathies may also prove useful for the treatment of many forms of RP

Acute and Protracted Cell Death in Light-Induced Retinal Degeneration in the Canine Model of Rhodopsin Autosomal Dominant Retinitis Pigmentosa

Purpose To characterize a light damage paradigm and establish structural and immunocytochemical measures of acute and protracted light-induced retinal degeneration in the rhodopsin (RHO) T4R dog model of RHO–autosomal dominant retinitis pigmentosa (ADRP). Methods Retinal light damage was induced in mutant dogs with a 1-minute exposure to various light intensities (0.1–1.0 mW/cm2) delivered with a Ganzfeld stimulator, or by fundus photography. Photoreceptor cell death was assessed by TUNEL assay, and alterations in retinal layers were examined by histology and immunohistochemistry 24 hours and 2 weeks after light exposure. Detailed topographic maps were made to document changes in the outer retinal layers of all four retinal quadrants 2 weeks post exposure. Results Twenty-four hours post light exposure, the severity of photoreceptor cell death was dose dependent. Immunohistochemical analysis revealed disruption of rod outer segments, focal loss of the RPE integrity, and an increase in expression of endothelin receptor B in Müller cells with the two highest doses of light and fundus photography. Two weeks after light exposure, persistence of photoreceptor death, thinning of the outer nuclear layer, and induction of Müller cell gliosis occurred with the highest doses of light. Conclusions We have characterized outcome measures of acute and continuing retinal degeneration in the RHO T4R dog following light exposure. These will be used to assess the molecular mechanisms of light-induced damage and rescue strategies in this large animal model of RHO-ADRP