Breathers and 'black' rogue waves of coupled nonlinear Schrödinger equations with dispersion and nonlinearity of opposite signs

Breathers and rogue waves of special coupled nonlinear Schrödinger systems (the Manakov equations) are studied analytically. These systems model the orthogonal polarization modes in an optical fiber with randomly varying birefringence. Studies earlier in the literature had shown that rogue waves can occur in these Manakov systems with dispersion and nonlinearity of opposite signs, and that the criterion for the existence of rogue waves correlates closely with the onset of modulation instability. In the present work the Hirota bilinear transform is employed to calculate the breathers (pulsating modes), and rogue waves are obtained as a long wave limit of such breathers. In terms of wave profiles, a ‘black’ rogue wave (intensity dropping to zero) and the transition to a four-petal configuration are elucidated analytically. Sufficiently strong modulation instabilities of the background may overwhelm or mask the development of the rogue waves, and such thresholds are correlated to actual physical properties of optical fibers. Numerical simulations on the evolution of breathers are performed to verify the prediction of the analytical formulations.postprin

Rich biomass combustion: Gaseous and particle number emissions

The cone calorimeter is a standard test method for material behaviour in fires. The principle of the cone calorimeter is to use an electric radiant heater to raise the temperature of the combustion zone and ignite the fuel. 35 kW/m 2 was used in the present work, as this has been previously shown to be sufficient to establish fully developed combustion of biomass materials such as wood. As one of the main fire loads is wood and wood is the dominant biomass for energy generation, it is reasonable to use the cone calorimeter to characterize the combustion of biomass on a small scale and pine was used in the present work. The cone calorimeter was used in the controlled atmosphere mode with an enclosure around the test biomass that enabled the air flow for biomass combustion to be controlled at 19.2 g/m 2 s, which corresponds to a combustion heat release rate HRR of 57 kW/m 2 , assuming all the oxygen in the air is consumed. This air flow will be shown to generate rich combustion at a metered equivalence ratio, Ø of about 2, which is comparable with the first gasification stage of biomass two stage burning in log burners and pellet burners, where air is added downstream of the gasification stage of biomass combustion. Soot emissions are generated in this rich gasification stage burning and potentially oxidized in the oxidation second stage burning. The rich burning gasification zone particulate emissions were analysed for number size distribution using the Cambustion DMS 500 particle size analyser. The exit from the controlled combustion zone was extended in a 75 mm diameter chimney where a mean gas sample was taken. A heated Gasmet FTIR was used for gas composition analysis, using a heated sample line, filter and pump from the sample point to the analyser. The particles emitted were sampled after the second stage combustion from entrained air into the chimney discharge gases into a dilution tunnel with a fixed gas flow rate of 24 l/s, which gave a dilution ratio of the primary combustion gases of 150/1 which is required for nano-particle size analysis. A Cambustion DMS500 electrical mobility particle number and size instrument was used with size resolution from 5 to 1000 nm. The present results show that in the rich burning first stage chimney sample there were very high levels of 20 nm nanoparticles, 1 × 10 10 /cc, and an accumulation mode peak at 200 nm. The presence of the 20 nm particles makes the particulate emissions extremely toxic

Impact of brodalumab treatment on psoriasis symptoms and health-related quality of life: use of a novel patient-reported outcome measure, the Psoriasis Symptom Inventory

Background: Psoriasis symptoms have a significant negative impact on health-related quality of life, impairing physical functioning and well-being. Objective: To evaluate the impact of brodalumab, a human anti-interleukin-17R monoclonal antibody, on psoriasis symptom severity as measured by a novel patient-reported outcome measure, the Psoriasis Symptom Inventory, and dermatology-specific health-related quality of life as measured by the Dermatology Life Quality Index (DLQI). Methods: This was a secondary analysis of a phase II, randomized, double-blind, placebo-controlled clinical study of patients with moderate-to-severe psoriasis (n = 198) treated with brodalumab or placebo. This analysis assessed Psoriasis Symptom Inventory scores and DLQI scores over time. Analyses were conducted on all patients who were randomized and received one or more injections of the study drug according to intention to treat using last observation carried forward to impute missing data. Results: At week 12, subjects in the brodalumab groups had significant improvements in mean Psoriasis Symptom Inventory total scores [8·5 (70 mg), 15·8 (140 mg), 16·2 (210 mg) and 12·7 (280 mg)] compared with placebo (4·8). Mean improvements in DLQI were clinically meaningful (≥ 5·7) in the brodalumab groups (6·2, 9·1, 9·6 and 7·1, respectively) and significantly greater than placebo (3·1). Improvements in Psoriasis Symptom Inventory were observed as early as week 2 and in DLQI by week 4. All eight Psoriasis Symptom Inventory item scores improved significantly among the brodalumab groups by week 12. Conclusions: Results were from a single randomized clinical trial and may not generalize to broader patient populations. However, treatment with brodalumab provided significant improvement in psoriasis symptoms in patients with moderate-to-severe psoriasis

On the study of the effects of sea views, greenery views and personal characteristics on noise annoyance perception at homes

2011-2012 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Vocabulary interventions for second language (L2) learners up to six years

This is a protocol for a Cochrane Review (intervention). The objectives are as follows:. The primary objective is to examine the immediate and long-term effects of second language (L2) vocabulary interventions targeting L2 learners up to six years of age on vocabulary and social-emotional well-being. The secondary objectives are to examine associations between L2 vocabulary interventions and general characteristics of L2 learners (e.g. age, L2 exposure and L1 skills), as well as specific characteristics of L2 learners who do not appear to benefit from treatment

Toxic Gas Emissions from Plywood Fires

Toxic emissions from four construction plywoods were investigated using a freely ventilated cone calorimeter with raw predilution hot gas sampling. Each plywood sample was exposed to the conical heater of the cone calorimeter radiating at 35 kw/m². Rich mixtures occurred in some of the tests, these rich mixtures produced high concentrations of toxic gases. The 4 samples had different peak heat release rate HRR, but similar steady state HRR. The elemental analysis of the four samples showed that they had different nitrogen content, indicating different glues were used. Plywood B had the highest N content of 6.43%, which resulted in the highest HCN concentration. The most important toxic species were CO, HCN, acrolein, formaldehyde and benzene on both an LC₅₀ and COSHH₁₅min basis

Quantum systems in weak gravitational fields

Fully covariant wave equations predict the existence of a class of inertial-gravitational effects that can be tested experimentally. In these equations inertia and gravity appear as external classical fields, but, by conforming to general relativity, provide very valuable information on how Einstein's views carry through in the world of the quantum.Comment: 22 pages. To be published in Proceedings of the 17th Course of the International School of Cosmology and Gravitation "Advances in the interplay between quantum and gravity physics" edited by V. De Sabbata and A. Zheltukhin, Kluwer Academic Publishers, Dordrech