2,480 research outputs found
Envelope solitons of nonlinear schrödinger equation with an anti-cubic nonlinearity
No full textOn the basis of a recently-proposed method to find solitary solutions of generalized nonlinear Schrödinger equations (Fedele R and Schamel H 2002 Eur. Phys. J. B 27 313, Fedele R 2002 Phys. Scr. 65 502, Fedele R, Schamel H and Shukla P K 2002 Phys. Scr. T 98 18), the existence of envelope solitonlike solutions of a nonlinear Schrödinger equation containing an anti-cubic nonlinearity (|ψ|-4ψ) plus a 'regular' nonlinear part is investigated. In particular, in the case that the regular nonlinear part consists of a sum of cubic and quintic nonlinearities (i.e. q 1|ψ|2ψ + q2|ψ|4ψ), an upper-shifted bright envelope solitonlike solution is explicitly found
Acoustic sensing of renal stone fragmentation in extracorporeal shockwave lithotripsy
No full textThis thesis describes the research carried out by the author on the exploitation of acoustic emissions
detected during extracorporeal shockwave lithotripsy (a non-invasive procedure for the treatment of
urinary stones) to develop a new diagnostic system. The work formed part of a research project on
lithotripsy undertaken by the University of Southampton in collaboration with Guy's and St Thomas'
NHS Foundation Trust (London) and a UK based company, Precision Acoustics Ltd (Dorchester). It
takes to a clinical conclusion the proposition made by Leighton and Coleman in 1992 that it might be
possible to build a sensor which would automatically exploit these passive acoustic emissions to
monitor the efficacy of a lithotripsy treatment. The work, predominantly experimental, involved both
in vitro and in vivo investigations. In particular, a first prototype diagnostic system (i.e. sensor plus
analysis software) was developed and tested in vitro during trials which included the use of a novel
cavitation sensor (on loan from the National Physical Laboratory, Teddington) and stone phantoms
designed by the author. This initial system was, then, refined and tested during clinical trials that
involved 130 patients. A preliminary trial on 51 patients aimed at refining the system and gathering
knowledge on the features of emissions recorded in vivo to produce an on-line monitoring system.
This trial was followed by other two trials that compared the output of the on-line acoustic system
against the ‘gold standard’ X-Ray assessment of treatments outcomes. The former of these two trials
involved 30 patients, and empirically defined the values of the key parameters (identified during the
in vitro tests) that would be used as the basis of the diagnosis. In particular, a classification rule of
treatments as being successful or unsuccessful was identified, and shown to agree significantly
(kappa=0.95) with the ‘gold standard’ follow-up assessment. The latter trial tested the final system
on 49 patients and confirmed an accurate treatment classification (kappa=0.94) in terms of the
successful/unsuccessful criterion
Vapor Pressure of Hydrofluoroolefins: Critical Review of Experimental Data and Models
No full textThis paper critically reviews vapor pressure data and vapor pressure models for seventeen hydrofluoroolefins, including R1234yf and R1234ze(E), and presents Wagner-type vapor pressure correlations for the seventeen hydrofluoroolefins
Diagnostic aids in the screening of oral cancer
No full textThe World Health Organization has clearly indentified prevention and early detection as major objectives in the control of the oral cancer burden worldwide. At the present time, screening of oral cancer and its pre-invasive intra-epithelial stages, as well as its early detection, is still largely based on visual examination of the mouth. There is strong available evidence to suggest that visual inspection of the oral mucosa is effective in reducing mortality from oral cancer in individuals exposed to risk factors. Simple visual examination, however, is well known to be limited by subjective interpretation and by the potential, albeit rare, occurrence of dysplasia and early OSCC within areas of normal-looking oral mucosa. As a consequence, adjunctive techniques have been suggested to increase our ability to differentiate between benign abnormalities and dysplastic/malignant changes as well as to identify areas of dysplasia/early OSCC that are not visible to naked eye. These include the use of toluidine blue, brush biopsy, chemiluminescence and tissue autofluorescence. The present paper reviews the evidence supporting the efficacy of the aforementioned techniques in improving the identification of dysplastic/malignant changes of the oral mucosa. We conclude that available studies have shown promising results, but strong evidence to support the use of oral cancer diagnostic aids is still lacking. Further research with clear objectives, well-defined population cohorts, and sound methodology is strongly required
The plasma wake field excitation: Recent developments from thermal to quantum regime
No full textTo describe the transverse nonlinear and collective self-consistent interaction of a long relativistic electron or positron beam with an unmagnetized plasma, a pair of coupled nonlinear differential equations were proposed by Fedele and Shukla in 1992 (Fedele, R. and Shukla, P. K. 1992a Phys. Rev. A 45, 4045). They were obtained within the quantum-like description provided by the thermal wave model and the theory of plasma wake field excitation. The pair of equations comprises a 2D Schrödinger-like equation for a complex wave function (whose squared modulus is proportional to beam density) and a Poisson-like equation for the plasma wake potential. The dispersion coefficient of the Schrödinger-like equation is proportional to the beam thermal emittance. More recently, Fedele-Shukla equations have been further applied to magnetized plasmas, and solutions were found in the form of nonlinear vortex states and ring solitons. They have been also applied to plasma focusing problems and extended from thermal to quantum regimes. We present here a review of the original approach, and subsequent developments
Piola’s approach to the equilibrium problem for bodies with second gradient energies. Part I: First gradient theory and differential geometry
No full textIn this study, some pioneering contributions, envisaged in the works of Gabrio Piola, were developed through tools of the modern differential geometry and applied to the second gradient continua. Part I introduced the variational approach for the equilibrium problem according to the first gradient theory and exploited differential geometric perspectives for the present scenario. By prescribing the stationarity of the Lagrangian energy functional, the virtual work equations for a Cauchy’s medium were recovered. The focus was on the deformation process regarded as a diffeomorphism between Riemannian embedded submanifolds, emphasizing the roles of the pullback metrics and of the covariant differentiation. Novel transport formulae were provided for normal and tangent vectors in the neighborhood of a boundary edge. The divergence theorem for curved surfaces with border was revisited, providing remarkable relationships between Lagrangian and Eulerian expressions involving projectors
sj-R-6-hpq-10.1177_13591053211064986 – for Examining commonsense epidemiology: The case of asthma
No full textsj-R-6-hpq-10.1177_13591053211064986 for Examining commonsense epidemiology: The case of asthma by Gabrielle Pogge, Erika A Waters, Gregory D Webster, David Fedele, Sreekala Prabhakaran and James A Shepperd in Journal of Health Psychology</p
Il gioco dell'amore e del caso (l'uomo fedele di Louis Garrel)
No full textIl film di Louis Garrel, L’uomo fedele, si iscrive nella tradizione francese del marivaudage. L’analisi de L’uomo fedele ripercorre le strategie narrative e le linee del gioco amoroso tra uomini e donne. Particolare attenzione è posta alle traiettorie degli sguardi che indicano precise posizioni dei personaggi. Sguardo e parola, da sempre elementi aurorali della relazione d’amore, dettano infatti all’interno del film le rispettive dinamiche, giocate su triangolazioni e passaggi speculari dei percorsi dei protagonisti. Inoltre Il fitto tessuto di citazioni del cinema della Nouvelle Vague testimonia la filiazione e la fedeltà a principi estetici della Nouvelle Vague (Truffaut e Godard) in una riscrittura al presente con altri occhi e altre parole
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