60 research outputs found
Partecipanti
No full textLuca Basso, Michele Basso, Alessio Brignani, Chiara Collamati, Maurizio Merlo, Valentina Moro, Luigi Pischedda, Fabio Raimondi, Marco Rampazzo Bazzan, Antonino Scalone, Paolo Scanga, Chiara Stenghel, Tania Toffanin, Stefano Visentin, Emiliano Zanelli..
Folding of Phase Noise Spectra in Charge-Pump Phase-Locked Loops Induced by Frequency Division
No full textIn charge-pump phase-locked loops, the reference signal samples the phase delay between reference and feedback signal. When a frequency divider is present in the loop, the spectrum folding of the VCO phase noise caused by the inherent sub-sampling operation adds a relevant contribution to the in-band output noise. This paper elaborates the discrete-time linear model of PLLs, in order to take into account spectrum folding, and provides a simple equation for the estimation of the output noise. The closed-form expressions are validated on the basis of behavioral simulations of a third-order charge-pump PLL
Camera Creatures: Rhetorics of Light and Emerging Media
No full textCamera Creatures addresses the new media landscape in which cameras, in most situations, outnumber pens. The dissertation argues that despite the accessibility and power of imagemaking devices, there persists in the humanities and social sciences a hesitation to engage the possibilities for composing with optical media. A number of factors contributing to this trend are addressed, including the preference for image analysis over imagemaking practices, persistent assumptions of the camera\u27s mechanical objectivity, and a tendency to teach visual invention as collage. As a counter-measure, a proposal is made for investment in the mediation of light, or \u27photonic rhetorics.\u27 To explore these effects in visual communication and the possibility of bringing them into practice, three emerging camera technologies are examined. The first, the photo app, focuses on the controversy surrounding embedded journalists who use social networks and the Hipstamatic camera phone application to relay stories of U.S. Marines deployed in Afghanistan. The chapter argues that the filters and shooting styles of these mobile apps encourage fluencies in the persuasive effects of light. The second camera technology, the video clip, addresses the long take as the predominant technique of everyday video-making. Film theory, video sharing trends, and circadian science contribute to a discussion of the rhythms of long-take shooting and its capability to expose both visual habits and the contingencies capable of disrupting them. The third site turns to video game \u27shooters\u27 and the virtual camera\u27s construction of \u27surrogate vision,\u27 which the author argues is a critical tool for understanding the future of mediated interactivity in both physical and digital landscapes. The dissertation concludes with a pedagogical section devoted to conscientious cheating. Alongside theories of deliberate practice, \u27cheating\u27 is repurposed for education, offering new ways of testing the \u27rules\u27 of optical composition while discovering opportunities to intervene in light\u27s constant mediation of perception
Ion beams of therapeutical energy on PMMA phantoms measurements in view of an innovative dose profiler realization for on line monitoring in hadrontherapy treatments
No full textCharacterization of a detector for β- radio-guided surgery
No full textThis paper reports a new device for the radio-guided surgery technique
exploiting beta- emitters. A specific intraoperative beta- detecting probe based on
a low-density organic crystal, the diphenylbutadiene-doped para-therphenyl, cou
pled by optical fibres to a photomultiplier, was developed.
A portable readout electronics was designed to provide the surgeons with multi real-time feedback. The
aspects related to the applicability of the device, in particular the perception of the
spatial resolution of the probe and the comprehension time necessary to the operator
to interpret the system response were investigated. Preliminary promising results
support the possibility of using this innovative probe in cancer surgery
A novel radioguided surgery technique exploiting β- decays
No full textThe background induced by the high penetration power of the Î3 radiation is the main limiting factor of the current radio-guided surgery (RGS). To partially mitigate it, a RGS with Î2+ -emitting radio-tracers has been suggested in literature. Here we propose the use of Î2- -emitting radio-tracers and Î2- probes and discuss the advantage of this method with respect to the previously explored ones: the electron low penetration power allows for simple and versatile probes and could extend RGS to tumours for which background originating from nearby healthy tissue makes Î3 probes less effective. We developed a Î2- probe prototype and studied its performances on phantoms. By means of a detailed simulation we have also extrapolated the results to estimate the performances in a realistic case of meningioma, pathology which is going to be our first in-vivo test case. A good sensitivity to residuals down to 0.1 ml can be reached within 1 s with an administered activity smaller than those for PET-scans thus making the radiation exposure to medical personnel negligible
Measurement of prompt photons and gamma PET from 80 MeV/u carbon beam on PMMA target
No full textThe measurements performed using a fully stripped carbon ions beam of 80MeV/u impinging on a Poly-methyl methacrylate (PMMA) phantom at the Laboratori Nazionali del Sud (LNS) dell'INFN in Catania, Italy, are shown. The study of the neutral particles production from the fragmentation of the Carbon Projectiles plays a crucial role in the present development and delivery of therapeutical beams for hadron therapy. Measurements performed monitoring PMMA phantoms are fundamental to validate MC simulations and confirm expected performances of detectors used for monitoring purposes. The feasibility of online dose monitoring has been investigated using LYSO detectors for prompt photons and NaI crystals for β + decays. © 2011 IEEE
Secondary radiation measurements for particle therapy applications: Nuclear fragmentation produced by 4He ion beams in a PMMA target
No full textNowadays there is a growing interest in particle therapy treatments exploiting
light ion beams against tumors due to their enhanced relative biological
effectiveness and high space selectivity. In particular promising results are
obtained by the use of 4He projectiles. Unlike the treatments performed
using protons, the beam ions can undergo a fragmentation process when
interacting with the atomic nuclei in the patient body. In this paper the results
of measurements performed at the Heidelberg Ion-Beam Therapy center are
reported. For the first time the absolute fluxes and the energy spectra of the
fragments—protons, deuterons, and tritons—produced by 4He ion beams of
102, 125 and 145 MeV u−1 energies on a poly-methyl methacrylate target
were evaluated at different angles. The obtained results are particularly
relevant in view of the necessary optimization and review of the treatment
planning software being developed for clinical use of 4He beams in clinical
routine and the relative bench-marking of Monte Carlo algorithm predictions
Monitoring of hadrontherapy treatments by means of charged particle detection
No full textThe interaction of the incoming beam radiation with the patient body in hadrontherapy
treatments produces secondary charged and neutral particles, whose detection can be
used for monitoring purposes and to perform an on-line check of beam particle range. In
the context of ion-therapy with active scanning, charged particles are potentially attractive
since they can be easily tracked with a high efficiency, in presence of a relatively low
background contamination. In order to verify the possibility of exploiting this approach
for in-beam monitoring in ion-therapy, and to guide the design of specific detectors, both
simulations and experimental tests are being performed with ion beams impinging on
simple homogeneous tissue-like targets (PMMA). From these studies, a resolution of the
order of few millimeters on the single track has been proven to be sufficient to exploit
charged particle tracking for monitoring purposes, preserving the precision achievable
on longitudinal shape. The results obtained so far show that the measurement of charged
particles can be successfully implemented in a technology capable of monitoring both
the dose profile and the position of the Bragg peak inside the target and finally lead to
the design of a novel profile detector. Crucial aspects to be considered are the detector
positioning, to be optimized in order to maximize the available statistics, and the capability
of accounting for the multiple scattering interactions undergone by the charged
fragments along their exit path from the patient body. The experimental results collected
up to now are also valuable for the validation of Monte Carlo simulation software tools
and their implementation in Treatment Planning Software packages
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