Progettazione e Sviluppo di una Web App per curve MD-spline

La tesi si occupa della progettazione e sviluppo di una Web App scritta in HTML5 e canvas e JavaScript che ha l'obiettivo di permettere di sperimentare le potenzialità di una nuova classe di curve 2D utili per il disegno denominata C1 MD-spline

Electronic Transport In Two-Dimensional Systems In The Quantum Hall Regime

The integer and the fractional quantum Hall effects are essential to the exploration of quantum matters characterized by topological phases. A quantum Hall system hosts one-dimensional (1D) chiral edge channels that manifest zero magnetoresistance, dissipationless due to the broken time reversal symmetry, and quantized Hall resistance v h e^2 with v being the topological invariant (or Chern number). The 1-1 correspondence between the conducting gapless edge channels to the gapped incompressible bulk states is a defining character of a topological insulator (TI). Understanding this correspondence in real systems, especially the origin of its robustness (in terms of the limit of breakdown), is important both fundamentally and practically (i.e. in relation to spintronics). However, the breakdown mechanism, especially in light of the edge-bulk correlation, is still an open question. We adopt GaAs two-dimensional (2D) high-mobility hole systems confined in a 20 nm wide (100)-GaAs quantum wells and have perform transport measurement for a range of charge densities between 4 and 5 x 10^10 cm^-2 with a carrier mobility of 2 – 4 x 10^6cm^2/Vs down to millikelvin temperatures. Systematic characterization of the 2D systems through Shubnikov-de Haas (SdH) oscillations yields an effective mass between 0.30 and 0.50m_e, in good agreement with the cyclotron resonance results. We then modify a regular Hall bar system into a unique anti-Hall bar geometry that provides an extra set of independent chiral edge channels without altering the topological invariant. We perform systematic measurement of quantum oscillations via chiral edges while simultaneously probing the bulk dynamics, through measuring across independent edges, in respond to the edge excitations. The edge-bulk correspondence reveals a non-equilibrium dynamical development of the incompressible bulk states that leads to a novel asymmetrical 1-0 Hall potential distribution. Moreover, probing the breakdown via inner and outer edges reveals a breakdown in discontinuous steps characterized by exactly the Landau level spacing. These results are the first-time evidence for a resonant quantum tunneling mechanism realized through aligning the edge and bulk energy levels. We also explored the fundamental physics of graphene-based devices with an eye focused on possible applications as ultra-high gain and quantum efficiency hybrid graphene-quantum dots phototransistors. We have confirmed that natural graphene presents better transport properties as mobility (10-fold higher) and delta point closer to zero. Also we have been able to observe the anomalous quantum Hall effect, unique to graphene, symbol of the high quality of the device. More experimental work is needed to gain more insights on the real efficiency of the devices and a more efficient fabrication

The Discussion between Leonardo Messinese and Emanuele Severino in View of a Rigorousization of Classical Metaphysics

This essay focusses on the proposal for the rigorousization of classical metaphysics that has been put forward by Leonardo Messinese, presenting his critical dialogue with Emanuele Severino concerning the originary truth of the being and its implications for the future of entities. The purpose of this paper is to solicit the continuation of the dialogue between Messinese and Severino, after having highlighted the reasons that lead Messinese to consider only partially convincing the solution provided by Severino about the complete understanding of the «variation» of the experience, which led him to re‐propose the «Principle of creation»

Uncertainties in lava flow hazard maps derived from numerical simulations: the case study of Mount Etna

The procedure for the derivation of a hazard map for lava flows at Mount Etna through lava flow simulations is critically reviewed. The DOWNFLOW code is then used to explore the sensitivity of the hazard map with respect to input settings. Three parameters are varied within ranges close to values recently applied to derive similar hazard maps: (i) the spacing between computational vents; (ii) the spatial probability density function (PDF) for future vent opening; and (iii) the expected length of future lava flows. The effect of increasing the spacing between computational vents tends to be compensated at the lower elevations, and a vent spacing smaller than about 500 m warrants an overall difference with respect to a reference map which is smaller than 6–8%. A random subsampling of the elements used to obtain the input vent opening PDF (−20%, −40% and −60%) originates significant but drastically smaller differences in the obtained map with respect to the reference one (~10%, ~12.5% and ~17% respectively, on average). In contrast, our results show that changes in the expected flow length originate, by far, the highest changes in the obtained hazard map, with overall differences ranging between ~20% and ~65%, and between ~30% and ~95% if computed only over inhabited areas. The simulations collected are further processed to derive maps of the confluence/diffluence index,which quantifies the error introduced, locally, when the position of the vent is misplaced by a given distance

A Microscopic Information System (MIS) for petrographic analysis

The database and visualization facilities of Geographic Information System (GIS) software are employed to support the analysis of rock texture from thin section by image processing. A Microscopic Information System (MIS) is hence obtained. The method is applied to transmitted light images of 137 samples obtained from 8 granitoid rocks. A slide scanner and a mount for crossed polarization are used to acquire the input images. For each thin section 5 collimated RGB images are scanned: 4 under different directions of crossed polarization and 1 without polarization. A grain segmentation procedure, based on two region growing functions is applied. The output is converted to vector format and refined using editing tools in the MIS environment, which enables a straightforward match between the input imagery and the final vectorized texture. GIS software provides optimal management of the MIS database, allowing the cumulative measurement of more than 87 000 grains

Capturing full resolution perspective and stereo views of large DEMs

A custom software to capture still views of images draped on digital surfaces is presented. It is called ViCam (for virtual camera). Unlike off the shelf software packages, our system is completely controlled by the user, allowing the visualization of a scene from an arbitrary viewpoint with an arbitrary (virtual) optic geometry (i.e. field of view angle). This software can work in loop over very large tiled datasets handled by a Geographic Information System (GIS) package, providing in output global views of the entire input area as single and seamless image layers at any desired resolution. Output image layers can be derived also in stereo anaglyph mode, allowing a thorough 3-dimensional perception of the landscape morphology as derived by the input elevation dataset. This method is here applied to two test cases showing the performances of the procedure. A website is also addressed where seamless perspective and stereo views of the landscape of the Italian territory preserving the input 10 m or 5 m resolution can be examined

Influence of fluctuating supply on the emplacement dynamics of channelized lava flows

The evolution of lava flows emplaced on Mount Etna (Italy) in September 2004 is examined in detail through the analysis ofmorphometricmeasurements of flow units. The growth of the main channelized flow is consistent with a layering of lava blankets, which maintains the initial geometry of the channel (although levees are widened and raised), and is here explicitly related to the repeated overflow of lava pulses. A simple analytical model is introduced describing the evolution of the flow level in a channelized flow unit fed by a fluctuating supply. The model, named FLOWPULSE, shows that a fluctuation in the velocity of lava extrusion at the vent triggers the formation of pulses, which become increasingly high the farther they are from the vent, and are invariably destined to overflow within a given distance. The FLOWPULSE simulations are in accordance with the observed morphology, characterized by a very flat initial profile followed by a massive increase in flow unit cross-section area between 600 and 700 m downflow. The modeled emplacement dynamics provides also an explanation for the observed substantial “loss” of the original flowing mass with increasing distance from the vent

An eighteen-month follow-up study on the effects of intravitreal dexamethasone implant in diabetic macular edema refractory to anti-VEGF therapy

Abstract AIM: To evaluate the long-term efficacy and safety of dexamethasone implants in subjects affected by diabetic macular edema (DME) resistant to anti-vascular endothelial growth factor (VEGF) therapy. METHODS: Thirty-two DME patients were enrolled. A 700 microgram slow release Intravitreal Dexamethasone Implant (Ozurdex®) was placed in the vitreous cavity. All patients were followed for 18mo. Best-corrected visual acuity (BCVA) measured with Early Treatment Diabetic Retinopathy Study (ETDRS) and central macular thickness (CMT) exams were carried out at baseline (T0) and after 1 (T1), 3 (T3), 4 (T4), 6 (T6), 9 (T9), 12 (T12), 15 (T15), and 18mo (T18) post injection. RESULTS: Repeated measures ANOVA showed an effect of treatment on ETDRS (P<0.0001). Post hoc analyses revealed that ETDRS values were significantly increased at T1, T3, T4, T9, and T15 (P<0.001) as compared to baseline value (T0). At T6, T12, and T18, ETDRS values were still statistically higher than baseline (P<0.001 vs T0). However, at these time points, we observed a trend to return to baseline conditions. ANOVA also showed an effect of treatment (P<0.0001). CMT decreased significantly at T1, T3, T4, T9, and T15 (P<0.001). At T6 (P<0.01), T12 and T18 (P<0.001) CMT was also significantly lower than T0 although a trend to return to the baseline conditions was also observed. CONCLUSION: Our findings demonstrate that Intravitreal Dexamethasone Implant is a good option to improve BCVA and CMT in DME patients resistant to anti-VEGF therapy. Our data also show that the use of drugs administered directly into the vitreous allows achieving appropriate and long-lasting concentration at the site of disease without systemic side effects