3,140 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
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
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
Cassandra Fedele and her Dalmatian correspondents
No full textU radu se analizira korespondencija trojice manje poznatih dalmatinskih humanista s Cassandrom Fedele, glasovitom mletačkom humanisticom s kraja 15. i početka 16. stoljeća. Riječ je o Benediktu Mišuliću iz Paga, Ambrozu Mihetiću iz Šibenika i Pavlu Paladiniću iz Hvara. Prva dvojica s Fedele su razmjenjivali pisma, a iz toga nam se dopisivanja sačuvalo po jedno pismo upućeno od Fedele Mišuliću i Mihetiću, kao i jedno odulje Mihetićevo pismo upućeno mletačkoj humanistici. Analiza tih pisama usredotočuje se prije svega na sadržajne pojedinosti koje pomažu da se rekonstruira tadašnja kulturna atmosfera u dalmatinskim gradovima i dopune spoznaje o njezinim akterima i književnoj komunikaciji među dvjema jadranskim obalama. Upozorava se također da Fedele Mišulića spominje u još najmanje dvama pismima, u kojima se, po svoj prilici, odvija komunikacija o njezinim pokušajima da osigura službu na španjolskom dvoru. Paladinić je pak Fedele posvetio jednu pohvalnu latinsku pjesmu u kojoj veliča njezinu učenost. Uz dopunjavanje spoznaja o trima dalmatinskim humanistima i njihovim kontaktima s Fedele, cilj je analize i obrada pojedinih retoričkih strategija koje se u spomenutim tekstovima primjenjuju. Na kraju rada razmatra se mogućnost da je adresat dvaju pisama Cassandre Fedele bio kotorski humanist Bernard Pima. Ta se pretpostavka odbacuje, ali se zato Pimi pokušavaju atribuirati dvije dosad nezapažene pjesme iz jednog rukopisa u Marciani.The paper analyzes the written correspondence between Cassandra Fedele, a renowned
Venetian Humanist from the end of the 15th and the beginning of the 16th century, and
three lesser-known Dalmatian Humanists - Benedikt Mišulić from Pag, Ambroz Mihetić
from Šibenik and Pavao Paladinić from Hvar. The first two exchanged letters with
Fedele; from their correspondence merely one of her letters to Mišulić and Mihetić has
been preserved, as well another longer letter Mihetić sent to the Venetian Humanist.
The analysis of those letters primarily focuses on the details of their content which
allow for the reconstruction of the cultural climate in Dalmatian cities and broadens our
understanding of its protagonists and the literary communication between the two Adriatic coasts. The paper also notes that Fedele mentions Mišulić in at least two other
letters in which she probably pleads for a position at the Spanish court. On the other
hand, Paladinić dedicated a laudatory poem in Latin to Fedele in which he praises her
erudition. Apart from widening our knowledge of the three Dalmatian Humanists and
their contacts with Fedele, the paper also analyzes specific rhetorical strategies the
texts employ. In the conclusion the paper considers the possibility that the addressee of
two Fedele’s letters might have been a Humanist from Kotor named Bernard Pima. The
assumption is nevertheless dismissed, but Pima is attributed with two overlooked poems from a manuscript in Marcian
Wave theories of non-laminar charged particle beams: from quantum to thermal regime
No full textThe standard classical description of non-laminar charged particle beams in paraxial approximation is extended to the context of two wave theories. The first theory that we discuss (Fedele R. and Shukla, P. K. 1992 Phys. Rev. A 45, 4045. Tanjia, F. et al. 2011 Proceedings of the 38th EPS Conference on Plasma Physics, Vol. 35G. Strasbourg, France: European Physical Society) is based on the Thermal Wave Model (TWM) (Fedele, R. and Miele, G. 1991 Nuovo Cim. D 13, 1527.) that interprets the paraxial thermal spreading of beam particles as the analog of quantum diffraction. The other theory is based on a recently developed model (Fedele, R. et al. 2012a Phys. Plasmas 19, 102106; Fedele, R. et al. 2012b AIP Conf. Proc. 1421, 212), hereafter called Quantum Wave Model (QWM), that takes into account the individual quantum nature of single beam particle (uncertainty principle and spin) and provides collective description of beam transport in the presence of quantum paraxial diffraction. Both in quantum and quantum-like regimes, the beam transport is governed by a 2D non-local Schrödinger equation, with self-interaction coming from the nonlinear charge-and current-densities. An envelope equation of the Ermakov-Pinney type, which includes collective effects, is derived for both TWM and QWM regimes. In TWM, such description recovers the well-known Sacherer's equation (Sacherer, F. J. 1971 IEEE Trans. Nucl. Sci. NS-18, 1105). Conversely, in the quantum regime and in Hartree's mean field approximation, one recovers the evolution equation for a single-particle spot size, i.e. for a single quantum ray spot in the transverse plane (Compton regime). We demonstrate that such quantum evolution equation contains the same information as the evolution equation for the beam spot size that describes the beam as a whole. This is done heuristically by defining the lowest QWM state accessible by a system of non-overlapping fermions. The latter are associated with temperature values that are sufficiently low to make the single-particle quantum effects visible on the beam scale, but sufficiently high to make the overlapping of the single-particle wave functions negligible. This lowest QWM state constitutes the border between the fundamental single-particle Compton regime and the collective quantum and thermal regimes at larger (nano-to micro-) scales. Comparing it with the beam parameters in the existing accelerators, we find that it is feasible to achieve nano-sized beams in advanced compact machines
Self-modulation of a long externally injected relativistic charged-particle beam in a laser wake field acceleration scheme. A preliminary quantum-like investigation
No full textRecent investigations indicate that sufficiently long beams of charged particles, travelling in a plasma, experience the phenomenon of self-modulation. The self-modulation is driven by the plasma wake field excitation due to the beam itself, and it may become unstable under certain conditions. A preliminary theoretical investigation of the self-modulation of a relativistic charged-particle beam in overdense plasma in the presence of a preformed plasma wave is carried out, within the quantum-like description of charged particle beams provided by the Thermal Wave Model. A simple physical model for the self-modulation is put forward, described by a nonlinear Schrodinger equation coupled with the Poisson-like equation for the plasma wake potential (so-called Fedele-Shukla equations). The physical mechanism is based on the interplay of three concomitant effects, the radial thermal dispersion (associated with the emittance epsilon), the radial ponderomotive effects of a preexisting plasma wave (which provides the guidance for the beam), and the self-interaction of the plasma wake field generated by the beam itself
Solitary waves in a Madelung Fluid Description of Derivative NLS equations
No full textRecently using a Madelung fluid description a connection between envelope-like solutions of
NLS-type equations and soliton-like solutions of KdV-type equations was found and investigated
by R. Fedele et al. (2002). A similar discussion is given for the class of derivative
NLS-type equations. For a motion with stationary profile current velocity the fluid density
satisfies generalized stationary Gardner equation, and solitary wave solutions are found. For
the completely integrable cases these are compared with existing solutions in literature
Studies of Magmatic Systems
No full textTwo magmatic systems were investigated using different petrological tools:
1) Origin of Ponza trachyte was studied combining data from MI with trends predicted by thermodynamic modeling. MI data were compared with known phase relations in the ternary feldspar and anorthite-diopside-albite systems to constrain the parameters used in the modeling. MI data are consistent with melt evolution from a basaltic parent via a fractional crystallization mainly of pyroxene and feldspars. These data and the results from the modeling, suggest a genetic link between the Ponza trachyte and coeval alkali olivine basalts on the nearby Ventotene Island.
2) We evaluated the range of magmatic temperatures within the crystallization interval for a basanite with different olivine-spinel geothermometers. While olivine spinel pair records the evolution of the basanite during crystallization, low temperatures calculated with the geothermometers are unrealistic. This is likely due to the presence of significant amounts of Ti in our magmatic spinels. Indeed Ti is not taken into account in the geothermometers. We tested the possibility of accounting for the presence and effects of Ti using a linear correction for the Fe+2 content in our spinels. While this generated more realistic temperatures at the low end of the range, it also increased the dispersion in the data, suggesting that spinel behavior is more complex and that the presence of Ti affects content and site occupancy of other elements as well.Ph. D
A Numerical Study on a Modified Arcan Test for Additive Manufacturing
No full textIn this communication reference was made to PolyLactic Acid products of 3D printing by Fused Filament Fabrication technique. To assess the fracture behavior of such manufactured parts, consistently with their transversal isotropy and brittle behavior, a modified Arcan fixture was proposed, allowing one to easily generate mixed mode loading conditions by a simple uniaxial testing machine. For a preliminary assessment of the novel equipment, a large-scale finite element model was developed. The model takes into account the presence of design tolerances and frictional contact between sample and fixture as well as interlaminar debonding within the sample, by means of explicit analyses including geometric nonlinearities. Computing costs and simulation accuracy were optimized by exploiting mass scaling, boundary conditions and diverse solutions for sample fastening
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