Analysis of Seeing-Induced Polarization Cross-Talk and Modulation Scheme Performance

We analyze the generation of polarization cross-talk in Stokes polarimeters by atmospheric seeing, and its effects on the noise statistics of spectropolarimetric measurements for both single-beam and dual-beam instruments. We investigate the time evolution of seeing-induced correlations between different states of one modulation cycle, and compare the response to these correlations of two popular polarization modulation schemes in a dual-beam system. Extension of the formalism to encompass an arbitrary number of modulation cycles enables us to compare our results with earlier work. Even though we discuss examples pertinent to solar physics, the general treatment of the subject and its fundamental results might be useful to a wider community.Comment: 33 pages, 7 figures; accepted in Astrophys.

Preliminary design of the Visible Spectro-Polarimeter for the Advanced Technology Solar Telescope

The Visible Spectro-Polarimeter (ViSP) is one of the first light instruments for the Advanced Technology Solar Telescope (ATST). It is an echelle spectrograph designed to measure three different regions of the solar spectrum in three separate focal planes simultaneously between 380 and 900 nm. It will use the polarimetric capabilities of the ATST to measure the full Stokes parameters across the line profiles. By measuring the polarization in magnetically sensitive spectral lines the magnetic field vector as a function of height in the solar atmosphere can be obtained, along with the associated variation of the thermodynamic properties. The ViSP will have a spatial resolution of 0.04 arcsec over a 2 arcmin field of view (at 600 nm). The minimum spectral resolving power for all the focal planes is 180,000. The spectrograph supports up to 4 diffraction gratings and is fully automated to allow for rapid reconfiguration.Comment: 8 pages, 5 figures, proceedings of SPIE Astronomical Telescopes + Instrumentation 2012 Conference 8446 (1-5 July 2012

L’onere di immediata impugnazione del bando e la necessità (o meno) di partecipare alla gara: dall’adunanza plenaria n. 1/2003 ai recenti sviluppi giurisprudenziali

Il presente contributo è volto a chiarire, attraverso la ricostruzione giurisprudenziale e dottrinaria,l’odierna portata dell’onere di immediata impugnazione delle clausole di bandi di gara e la connessa problematica della necessità, in tale ipotesi, di partecipare alla gara per avere legittimazione al ricorso.La tematica coinvolge dalle fondamenta i caratteri del sistema di giustizia amministrativa poiché attiene alle condizioni cui è subordinata la proposizione del ricorso giurisdizionale,ovverosia l’interesse ad agire e la legittimazione al ricorso.L’analisi darà prima conto dell’evoluzione interpretativa sul tema dell’onere di immediata impugnazione e, più in generale, dell’interesse a ricorrere; successivamente, si concentrerà sul problema, solo apparentemente subordinato, della necessità di prendere parte alla gara e, più in generale, sulla condizione di legittimazione al ricorso

Geometric modular action for disjoint intervals and boundary conformal field theory

In suitable states, the modular group of local algebras associated with unions of disjoint intervals in chiral conformal quantum field theory acts geometrically. We translate this result into the setting of boundary conformal QFT and interpret it as a relation between temperature and acceleration. We also discuss aspects ("mixing" and "charge splitting") of geometric modular action for unions of disjoint intervals in the vacuum state.Comment: Dedicated to John E. Roberts on the occasion of his 70th birthday; 24 pages, 3 figure

Recycling of yttria-stabilized zirconia waste powders in glazes suitable for ceramic tiles

The aim of this work is to demonstrate the feasibility of valorizing and recycling Yttria-stabilized Zirconia thermal spray waste into high value products for industrial and residential use. Based on the powders chemistry and morphology, this work aims to realize products, like frits suitable for white glazes and ceramic tiles. The focus is on one class of powder: high-temperature and abrasion-resistant ceramics, like Yttria-stabilized zirconia. This study has revealed that the substitution of pure zirconia with waste Yttria-stabilized zirconia is possible in high percentages, up to 100% to prepare frits suitable for white glaze

Dispersion of carbon nanotubes in melt compounded polypropylene based composites investigated by THz spectroscopy

We investigate the use of Terahertz (THz) Time Domain Spectroscopy (TDS) as a tool for the measurement of the index dispersion of multi-walled carbon nanotubes (MWCNT) in polypropylene (PP) based composites. Samples containing 0.5% by volume concentration of non-functionalized and functionalized carbon nanotubes are prepared by melt compounding technology. Results indicate that the THz response of the investigated nanocomposites is strongly dependent on the kind of nanotube functionalization, which in turn impacts on the level of dispersion inside the polymer matrix. We show that specific dielectric parameters such as the refractive index and the absorption coefficient measured by THz spectroscopy can be both correlated to the index of dispersion as estimated using conventional optical microscopy