The use of India ink in tissue-simulating phantoms

The optical properties of India ink, an absorber often used in preparation of tissue simulating phantoms, have been investigated at visible and near infrared wavelengths. The extinction coefficient has been obtained from measurements of collimated transmittance and from spectrophotometric measurements, the absorption coefficient from multidistance measurements of fluence rate in a diffusive infinite medium with small concentrations of added ink. Measurements have been carried out on samples of India ink from five different brands, and for some brands also from different batches. As also reported in previously published papers the results we have obtained showed large inter-brand and inter-batch variations for both the absorption and the extinction coefficient. On the contrary, our results showed small variations for the ratio between the absorption and the extinction coefficient. The albedo is therefore similar for all samples: The values averaged over all samples investigated were 0.161, 0.115, and 0.115 at λ = 632.8, 751, and 833 nm respectively, with maximum deviations of 0.044, 0.019, and 0.035. These results indicate that, using the values we have obtained for the albedo, it should be possible to obtain with uncertainty smaller than about 4% the absorption coefficient of a sample of unknown ink from simple measurements of extinction coefficient. A similar accuracy is not easily obtained with the complicated procedures necessary for measurements of absorption coefficient

Effect of dependent scattering on the optical properties of Intralipid tissue phantoms

The calibration of optical tissue-simulating phantoms remains an open question in spite of the many techniques proposed for accurate measurements of optical properties. As a consequence, a reference phantom with well known optical properties is still missing. As a first step towards a reference phantom we have recently proposed to use dilutions of Intralipid 20%. In this paper we discuss a matter that is commonly ignored when dilutions are prepared, i.e., the possibility of deviations from the simple linear relationships between the optical properties of the dilution and the Intralipid concentration due to the effects of dependent scattering. The results of an experimental investigation showed that dependent scattering does not affect absorption. As for the reduced scattering coefficient the effect can be described adding a term proportional to the square of the concentration. However, for concentrations of interest for tissue optics deviations from linearity remain within about 2%. The experimental investigation also showed that the microphysical properties of Intralipid are not affected by dilution. These results show the possibility to easily obtain a liquid diffusive phantom whose optical properties are known with error smaller than about 1%. Due to the intrinsic limitations of the different techniques proposed for measuring the optical properties it seems difficult to obtain a similar accuracy for solid phantoms

Il microcarcinoma papillare della tiroide. Implicazioni cliniche e strategia terapeutica

Gli Autori riportano la propria esperienza sulle implicazioni cli - niche e le strategie terapeutiche del microcarcinoma papillare della tiroide, valutando 412 pazienti sottoposti ad intervento chirurgico per patologia tiroidea. Essi sottolineano l’attuale problematica della diagnosi “incidentale” postoperatoria, la relativa strategia terapeutica adiuvante, il frequente riscontro di una patologia tiroidea benigna associata, fattori che giustificano, oltre le note motivazioni oncologi - che, la scelta della tiroidectomia totale di principio

Politica industriale e sviluppo sostenibile

Il libro riproduce ed amplia le relazioni presentate al workshop del 3 ottobre 2014 presso il Dipartimento di Economia dell’Università di Parma, ad opera di studiosi appartenenti all’Università di Ferrara, allo Iefe-Università Bocconi di Milano, all’Università di Modena, alla Scuola Sant’Anna di Pisa, nonché alla stessa Università di Parma. I cinque contributi qui presentati fotografano cinque diversi aspetti del rapporto fra politica industriale (più in generale crescita economica diretta dalle istituzioni pubbliche) e sviluppo sostenibile: a livello nazionale, il possibile trade-off fra i due obiettivi di politica industriale e di sostenibilità ambientale nel tentativo di gerarchizzare i “settori strategici”, e la necessità che questo trade-off sia parzialmente compensato a livello di sforzo innovativo (Di Tommaso e Tassinari); a livello internazionale, la possibilità che politiche industriali nazionali non operino all’interno di un gioco a somma zero, ma diano risultati favorevoli al raggiungimento di un bene pubblico globale quale il cambiamento climatico (Fabbri e Ninni); a livello di imprese, la tendenziale riduzione delle contraddizioni fra incentivi al loro operare e “impronta” ambientale, grazie agli accordi volontari e in particolare all’importante ruolo della certificazione (Frey); a livello di istituzioni, l’esistenza di tipologie diverse di obiettivi e di strumenti a livello nazionale e a livello locale, e l’analisi in un confronto tra paesi europei delle caratteristiche delle politiche ambientali impostate a livello sub-nazionale (Croci e Molteni); a livello di mercato del lavoro, l’effetto sul tessuto industriale delle politiche di aumento della flessibilità del lavoro nella singola impresa, come aspetto particolare di una ridiscussione più ampia del concetto di sostenibilità ambientale e dei suoi rapporti con la politica nei confronti delle imprese (Giovannetti)

Absorption and scattering properties of carbon nanohorn-based nanofluids for direct sunlight absorbers

In the present work, we investigated the scattering and spectrally resolved absorption properties of nanofluids consisting in aqueous and glycol suspensions of single-wall carbon nanohorns. The characteristics of these nanofluids were evaluated in view of their use as sunlight absorber fluids in a solar device. The observed nanoparticle-induced differences in optical properties appeared promising, leading to a considerably higher sunlight absorption with respect to the pure base fluids. Scattered light was found to be not more than about 5% with respect to the total attenuation of light. Both these effects, together with the possible chemical functionalization of carbon nanohorns, make this new kind of nanofluids very interesting for increasing the overall efficiency of the sunlight exploiting device

Forward solvers for photon migration in the presence of highly and totally absorbing objects embedded inside diffusive media

n/

Preliminary Analysis of the Effects of the Ground Plane on the Element Patterns of SKA1-Low

Each station of the SKA1-Low radio telescope is composed by 256 dual-polarized log-periodic antennas deployed over a metallic ground plane with 42 m diameter. This station is usually modelled in EM simulators by considering an infinite ground plane, which drastically reduces the computational time. This contribution shows that a finite ground plane can bring to quite significant differences in some embedded element patterns with respect to the infinite ground plane case. Furthermore, we show the impact on the antenna pattern of different dielectric media surrounding the finite ground plane. For instance, at 50 MHz the maximum of the antenna gain decreases by 5% for the terrain with 10% moisture level

Impact of mutual coupling between SKALA4.1 antennas to the spectral smoothness response

One of the advantages of arrays with aperiodic distributed elements is their ability to mitigate the detrimental mutual coupling effects on the radiation pattern. However, we show that the mutual coupling inside a random array can still generate undesired structures in the frequency response although the single antenna features a spectral smooth response. For small subsets (a couple of SKALA4.1 antennas and a 16-element array) of a low-frequency instrument station of the Square Kilometre Array, the combination of large mutual coupling and antenna geometry creates systematic distortions in the element frequency responses. This phenomenon compromises the station spectral smoothness response versus frequency. However, we demonstrate that it is possible to partially mitigate these frequency structures by reconfiguring the antenna distribution based on exclusion zones

Mutual Coupling Analysis for a SKA1-LOW Station

The modelling of the antenna patterns represents one of the main challenges for the instrumental calibration of radio telescopes composed by antennas randomly distributed. In this work, the electromagnetic characterization of a single station of the low-frequency instrument of the Square Kilometre Array (SKA) radio telescope operating from 50 to 350 MHz is reported. The station is assumed to be composed by Log Periodic antennas. The effects of mutual coupling on the complex embedded element patterns and on the array beam are investigated by means of a full-wave electromagnetic analysis. The accuracy of a simplified, mutual coupling-free approach is presented as well

Using Embedded Element Patterns to Improve Aperture Array Calibration

Several existing and planned low-frequency (<; 350 MHz) radio astronomical facilities exploit subarrays or stations consisting of receiving elements in an irregular configuration. Calibration of the RF path of each receiving element is crucial for accurate beamforming with these stations. Currently used station calibration methods usually assume that the embedded element patterns (EEPs) of the receiving elements within a station are identical. In this contribution, we show that ignoring the inter-element EEP variations causes systematic errors in the calibration results using the stations of the low-frequency receiving systems of the Square Kilometre Array (SKA) and the Low Frequency Array (LOFAR) as examples. We show that the magnitude of these errors increases with increasing EEP variations. We also discuss the challenges faced by SKA and LOFAR to mitigate these errors by exploiting a priori knowledge of the EEPs