Jacobi multipliers, non-local symmetries and nonlinear oscillators

Constants of motion, Lagrangians and Hamiltonians admitted by a family of relevant nonlinear oscillators are derived using a geometric formalism. The theory of the Jacobi last multiplier allows us to find Lagrangian descriptions and constants of the motion. An application of the jet bundle formulation of symmetries of differential equations is presented in the second part of the paper. After a short review of the general formalism, the particular case of non-local symmetries is studied in detail by making use of an extended formalism. The theory is related to some results previously obtained by Krasil'shchi, Vinogradov and coworkers. Finally the existence of non-local symmetries for such two nonlinear oscillators is proved.Comment: 20 page

The effect of stepping down combination therapy on airway hyperresponsiveness to mannitol

SummaryRationaleControversy exists about the safety of long acting beta2-agonist (LABA) treatment, in particular in children. Combination therapy with a LABA and an inhaled corticosteroid (ICS) is prescribed to children with moderate asthma and can be stepped down by withdrawal of the LABA when asthma is well controlled.ObjectiveTo analyze the effect of stepping down from LABA/ICS combination therapy to monotherapy with the same dose of ICS on the airway response to mannitol in asthmatic children.Methods17 children, aged 12–17 years, with clinically stable asthma, receiving combination therapy, were analyzed in this observational prospective open-label study. Children performed a mannitol challenge at baseline and 30±4 days after their medication was stepped down to ICS monotherapy. The changes in the provoking dose of mannitol to cause a 15% fall in FEV1 (PD15), response-dose ratio and recovery time following a short acting beta2-agonist to ≥95% of baseline FEV1 were assessed.ResultsMannitol PD15 and response-dose ratio did not significantly change after stepping down. The recovery time following a short acting beta2-agonist to ≥95% of baseline FEV1 was significantly shorter (p=0.01) after the withdrawal of the LABA.ConclusionsIn short-term follow-up, stepping down clinically stable asthmatic children from combination therapy to monotherapy with an ICS does not change airway hyperresponsiveness (AHR) to mannitol but does shorten recovery time to baseline lung function following a rescue short acting beta2-agonist

System Tests of the ATLAS Pixel Detector

The innermost part of the ATLAS (A Toroidal LHC ApparatuS) experiment at the LHC (Large Hadron Collider) will be a pixel detector, which is presently under construction. Once installed into the experimental area, access will be extremely limited. To ensure that the integrated detector assembly operates as expected, a fraction of the detector which includes the power supplies and monitoring system, the optical readout, and the pixel modules themselves, has been assembled and operated in a laboratory setting for what we refer to as system tests. Results from these tests are presented.Comment: 5 Pages, 9 Figures, to appear in Proceedings of the Eleventh Workshop on Electronics for LHC and Future Experiment

A new life for sterile neutrino dark matter after the pandemic

We propose a novel mechanism to generate sterile neutrinos $\nu_s$ in theearly Universe, by converting ordinary neutrinos $\nu_\alpha$ in scatteringprocesses $\nu_s\nu_\alpha\to\nu_s\nu_s$. After initial production byoscillations, this leads to an exponential growth in the $\nu_s$ abundance. Weshow that such a production regime naturally occurs for self-interacting$\nu_s$, and that this opens up significant new parameter space where $\nu_s$make up all of the observed dark matter. Our results provide strong motivationto further push the sensitivity of X-ray line searches, and to improve onconstraints from structure formation.<br

Pyrolysis of plastic waste: effect of feedstock pretreatment and fate of contaminants

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A new life for sterile neutrino dark matter after the pandemic

We propose a novel mechanism to generate sterile neutrinos $\nu_s$ in the early Universe, by converting ordinary neutrinos $\nu_\alpha$ in scattering processes $\nu_s\nu_\alpha\to\nu_s\nu_s$. After initial production by oscillations, this leads to an exponential growth in the $\nu_s$ abundance. We show that such a production regime naturally occurs for self-interacting $\nu_s$, and that this opens up significant new parameter space where $\nu_s$ make up all of the observed dark matter. Our results provide strong motivation to further push the sensitivity of X-ray line searches, and to improve on constraints from structure formation

A new life for sterile neutrino dark matter after the pandemic

We propose a novel mechanism to generate sterile neutrinos $\nu_s$ in theearly Universe, by converting ordinary neutrinos $\nu_\alpha$ in scatteringprocesses $\nu_s\nu_\alpha\to\nu_s\nu_s$. After initial production byoscillations, this leads to an exponential growth in the $\nu_s$ abundance. Weshow that such a production regime naturally occurs for self-interacting$\nu_s$, and that this opens up significant new parameter space where $\nu_s$make up all of the observed dark matter. Our results provide strong motivationto further push the sensitivity of X-ray line searches, and to improve onconstraints from structure formation.<br

(Non)local Hamiltonian and symplectic structures, recursions, and hierarchies: a new approach and applications to the N=1 supersymmetric KdV equation

Using methods of math.DG/0304245 and [I.S.Krasil'shchik and P.H.M.Kersten, Symmetries and recursion operators for classical and supersymmetric differential equations, Kluwer, 2000], we accomplish an extensive study of the N=1 supersymmetric Korteweg-de Vries equation. The results include: a description of local and nonlocal Hamiltonian and symplectic structures, five hierarchies of symmetries, the corresponding hierarchies of conservation laws, recursion operators for symmetries and generating functions of conservation laws. We stress that the main point of the paper is not just the results on super-KdV equation itself, but merely exposition of the efficiency of the geometrical approach and of the computational algorithms based on it.Comment: 16 pages, AMS-LaTeX, Xy-pic, dvi-file to be processed by dvips. v2: nonessential improvements of exposition, title change

How UK HE STEM Students Were Motivated to Switch Their Cameras on: A Study of the Development of Compassionate Communications in Task-focused Online Group Meetings

© 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/)HE’s pandemic-driven shift to online platforms has increased social and learning disconnection amongst students. In online group work/teamwork, many are reluctant to switch on their cameras to be more present to others. Compassion in group work/teamwork is defined as noticing, not normalizing, one’s own and/or others’ distress or disadvantaging and taking wise action to prevent or reduce this. This notion of compassion is being assessed in the HE sector using filmed task-focused in-class group work meetings to identify levels of both inclusivity and criticality around the team. This study investigates the use and outcomes of using the compassionate communications strategies (that were developed in and for the offline classroom) in online team meetings. In this mixed-methods study, two groups of four international STEM students, each from a sample of five UK universities, were video-recorded in task-focused group work meetings (TGMs) before and after an online interactive 90-min training session (‘the intervention’) on the Cognitive Skills of Compassionate Communications (CSCC) in teams. A comparison of the (pre and post CSCC intervention) quantitative and qualitative data results indicated, post-intervention, a significant increase in students’ screen gaze attentiveness to each other, and reasons why students’ motivation to switch on their cameras had changed.Peer reviewedFinal Published versio