508 research outputs 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
Alle origini dell'Antropologia italiana
No full textStoria Antropologia italiana e napoletana; ricerche e rapporti internazionali di Giustiniano Nicolucc
Inconstant Planck's constant
No full textMotivated by the Dirac idea that fundamental constants are dynamical variables and by conjectures on quantum structure of space–time at small distances, we consider the possibility that Planck constant ħ is a time depending quantity, undergoing random Gaussian fluctuations around its measured constant mean value, with variance σ2 and a typical correlation timescale Δt. We consider the case of propagation of a free particle and a one-dimensional harmonic oscillator coherent state, and show that the time evolution in both cases is different from the standard behavior. Finally, we discuss how interferometric experiments or exploiting coherent electromagnetic fields in a cavity may put effective bounds on the value of τ = σ2Δt
Fenomeni magnetici ed elettromagnetici, Una proposta didattica basata su un percorso di esperimenti
No full text
Electrocardiographic tips in a young woman presenting with ST-elevation myocardial infarction
No full textnon
Aerothermodynamics and thermal design for on-ground and in-flight testing of a deployable heat shield capsule
No full textThe article deals with the aerothermodynamic and thermal analysis of two technological demonstrators suitable for research activities on deployable heatshield entry capsules. Variable geometry bodies represent a formidable way to build low ballistic coefficient entry platforms able to limit convective heat fluxes, mechanical loads, and final descent velocity. These characteristics suggest several interesting applications for space missions such as to exploit those systems for human or large payloads landing on Mars. The main feature of the demonstrators is the umbrella-like deployable heatshield made of a flexible thermal protection system. In this framework, the work reports on the design analyses carried out for a flight and a ground demonstrator developed to prove, with suborbital flight and plasma wind tunnel test campaigns, several key technologies of the deployable heatshield. Several non-equilibrium three-dimensional flowfield simulations were performed to assess the aerothermal loading conditions expected for the demonstrators. Pressure and heat flux distributions on the deployable heatshield are provided and discussed. Finally, those surface loading conditions are set to feed a finite-element thermal analysis of the demonstrators, also detailed in the work
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