13,049 research outputs found
Transient and chaotic low-energy transfers in a system with bistable nonlinearity
The low-energy dynamics of a two-dof system composed of a grounded linear oscillator coupled to
a lightweight mass by means of a spring with both cubic nonlinear and negative linear components
is investigated. The mechanisms leading to intense energy exchanges between the linear oscillator,
excited by a low-energy impulse, and the nonlinear attachment are addressed. For lightly damped
systems, it is shown that two main mechanisms arise: Aperiodic alternating in-well and cross-well
oscillations of the nonlinear attachment, and secondary nonlinear beats occurring once the dynamics
evolves solely in-well. The description of the former dissipative phenomenon is provided in a
two-dimensional projection of the phase space, where transitions between in-well and cross-well
oscillations are associated with sequences of crossings across a pseudo-separatrix. Whereas the second
mechanism is described in terms of secondary limiting phase trajectories of the nonlinear
attachment under certain resonance conditions. The analytical treatment of the two aformentioned
low-energy transfer mechanisms relies on the reduction of the nonlinear dynamics and consequent
analysis of the reduced dynamics by asymptotic techniques. Direct numerical simulations fully
validate our analytical predictions
Hunting for heavy composite Majorana neutrinos at the LHC
We investigate the search for heavy Majorana neutrinos stemming from a
composite model scenario at the upcoming LHC Run II at a center of mass energy
of 13 TeV. While previous studies of the composite Majorana neutrino were
focussed on gauge interactions via magnetic type transition coupling between
ordinary and heavy fermions (with mass ) here we complement the composite
model with contact interactions at the energy scale and we find that
the production cross sections are dominated by such contact interactions by
roughly two/three orders of magnitude. This mechanism provides therefore very
interesting rates at the prospected luminosities. We study the same sign
di-lepton and di-jet signature () and perform a fast
detector simulation based on Delphes. We compute 3 and 5
contour plots of the statistical significance in the parameter space
(). We find that the potentially excluded regions at TeV are quite larger than those excluded so far at Run I considering
searches with other signatures.Comment: 14 pages, 9 figures, Minor comments and few references added. Version
accepted by the European Physical Journal C (EPJC
SmokeFree Sports Project Report
Children and young people are amongst the most vulnerable groups in society and are highly susceptible to smoking experimentation and addiction. In Liverpool, smoking prevalence is significantly higher than the UK average. Therefore early intervention strategies are required for smoking prevention and cessation. Research has found a negative association between smoking and physical activity. SmokeFree Sports aims to explore whether physical activity and sport can be used to promote the smoke free message to children and young people.
SmokeFree Sports is an innovative multi-dimensional campaign that incorporates social-marketing strategies alongside the provision of sports and physical activities to: a) de-normalise smoking among youth b) empower youth to stay smoke free, and c) increase awareness of the dangers of smoking using positive messaging through the medium of sport and physical activity. This project is delivered across Liverpool and aims to reduce the prevalence of smoking and prevent the uptake of smoking in children and young people.
The initiative, which is managed by Liverpool John Moores University in partnership with Liverpool PCT, employs a variety of strategies to promote and deliver the smoke free message to children and young people including a) training sports coaches and teachers to deliver the smoke free message, b) delivering SFS messages in schools and youth clubs through sport and physical activity, c) asking children to sign a pledge to be smoke free, d) support voluntary sports clubs to adopt a smoke free policy on their playing fields, e) encouraging organizations and individuals interested in health and sport to sign up to the SmokeFree Sports Charter and f) signposting children to smoking cessation services
Conformations Of A Model Protein Revealed By An Aggregating Cuᴵᴵ Porphyrin: Sensing The Difference
Aggregated t-CuP binds to poly-L-glutamate through supramolecular interactions, revealing itself to be an extremely sensitive probe for the major conformations of the polymeric scaffold
Absence of Metastable States in Strained Monatomic Cubic Crystals
A tetragonal (Bain path) distortion of a metal with an fcc (bcc) ground state
will initially cause an increase in energy, but at some point along the Bain
path the energy will again decrease until a local minimum is reached. Using a
combination of parametrized tight-binding and first-principles LAPW
calculations we show that this local minimum is unstable with respect to an
elastic distortion, except in the rare case that the minimum is at the bcc
(fcc) point on the Bain path. This shows that body-centered tetragonal phases
of these materials, which have been seen in epitaxially grown thin films, must
be stabilized by the substrate and cannot be free-standing films.Comment: 7 pages, 5 postscript figures, REVTEX, submitted to Phys. Rev.
Nomenclature adjustments and new syntaxa of the arctic, alpine and oro-Mediterranean vegetation
Proposte sintassonomiche e nomenclaturali per la vegetazione della Tundra alpina. Il capitolo riguardante l'alta quota appenninica è il più corposo e propone il nuovo syntaxon Leontopodio-Elynion a livello di alleanza. La grande novità sta nel fatto che questa alleanza è da considerarsi anfi-Adriatica e unsice Appennino e balcani, differenziandosi dall'alleanza già definita da altri per le Alpi. i Pirenei e i Carpazi.During preparation of the European checklist of vegetation units (EuroVegChecklist), it became clear that some earlier described syntaxa need to be typified in order to stabilize nomenclature and some new syntaxa need to be described. Here we propose nomenclature adjustments and formal description of four new alliances
for the Arctic, alpine and oro-Mediterranean vegetation of Europe, Greenland and Anatolia. First, we typify the class Juncetea trifidi. Second, we describe four new alliances, such as the Puccinellion nuttallianae (Low-Arctic salt steppes of Greenland; class Saxifrago tricuspidatae-Calamagrostietea purpurascentis), Dryado octopetalae-
Caricion arctisibiricae (Arctic tundra vegetation of north-eastern European Russia; class Carici rupestris-Kobresietea bellardii), Leontopodio nivalis-Elynion myosuroidis (southern European alpine tundra vegetation; class Carici rupestris-Kobresietea bellardii) and Lagotido uralensis-Caricion ensifoliae (alpine tundra vegetation of the Southern Ural Mountains; class Juncetea trifidi). Two new associations are described within the first two of these alliances. Finally, we present an interpretation of the alliance Muscario-Scillion nivalis
Effect Of Zinc Cations On The Kinetics Of Supramolecular Assembly And The Chirality Of Porphyrin J-Aggregates
Dilute aqueous solutions of anionic meso-4-sulfonatophenyl-porphyrin (TPPS) extract zinc(ii) ions from glass or quartz surfaces at room temperature and efficiently form the corresponding metal complex (ZnTPPS). The partial or complete formation of ZnTPPS has been probed by UV/Vis spectroscopy and both static and time-resolved fluorescence. The source of zinc(ii) ions has been clearly identified through inductively coupled plasma optical emission spectrometry. The presence of increasing amounts of ZnTPPS slows down the rate of TPPS J-aggregate formation in acid solution. This influences the nucleation step and has a profound impact on the onset of chirality in these species. This evidence indicates the important role of this adventitious metal ion in the interpretation of various spectroscopic and kinetic data for the self-assembly of the TPPS porphyrin and provides some insights into controversial findings on their chirality. The use of this metal derivative as the starting compound for in situ formation of monomeric TPPS is suggested
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