Migration flows, structural change, and growth convergence: A panel data analysis of Italian regions

The aim of this paper is to measure the impact of migration flows on growth via their effect on structural change. To this extent we build an empirical growth model in which migration flows and intersectoral wage differentials can affect the speed of labour readjustment between sectors and, ultimately, total factor productivity and growth. By employing Italian regional data stemming over more than four decades we measure the effects of interregional migration on regional growth and convergence. The results confirm that migration in general, and in particular the content of human capital of moving workers, is a relevant factor in determining the speed of technological change and growth.Migration; Structural change; Growth and convergence.

Development of an efficient and thermally controlled Raman system for fast and safe molecular characterization of paint layers

An innovative high-efficiency Raman system (exc. wav. 1064 nm) for safe molecular characterization of paint layers and other photosensitive materials has been developed and successfully tested. It was equipped with a novel optical probe, which has been designed and built in order to perform Raman scattering measurements on a relatively large spot at laser intensities lower than the typical ones of the commercial instruments. Original optical solutions were implemented in order to achieve such improved efficiency. Furthermore, the instrument was also equipped with an active thermal control line allowing to prevent alterations of the material under study and to optimize the measurement cycles by means of suitable modulations of the laser power. Comparative tests using the novel analytical tool and an alternative setup based on a commercial Raman probe were carried out on a set of pure pigments and oil paint layers, which allowed assessing the significantly higher efficiency and reliability of the former with respect to the latter

Spectroscopic assessment of the UV laser removal of varnishes on paint substrates

TECHNART 2015 − Catania, April 27 - 30, 2015; http://technart2015.lns.infn.it/The removal/thinning of aged varnishes from easel paintings is a very complex issue, which involves the need of finely-optimized conservation treatments for preserving both the pictorial substrates and the remaining varnish film. To this goal, cleaning techniques based on laser ablation may satisfy these requirements, especially when wavelengths and pulse durations are accurately selected. Recently, with the aim of minimizing photo-thermal, photo-mechanical and photo-chemical phenomena, ultra-short lasers operating in picosecond and femtosecond regimes have been introduced in the field [1-2]. Processing of fresh mastic and dammar varnishes with 248 nm, 500 fs laser pulses results in an improved etched morphology as compared with ns pulses of the same wavelength [1]. Irradiation of shellac at 213 nm with pulses of 15 ns of photo-sensitive tempera paint models covered with shellac allows controlled micrometric removal without affecting the surface morphology and chemical composition of the remaining varnish film and underlying paint layers. However, fs multiple pulse Ti:Sapphire irradiation of films of this varnish at 795, 398 and 265 nm has turned out to be ineffective for removing shellac varnish from egg-yolk based tempera paints [2]. Taking advantage from the latest findings, in the present work we focus on the assessment of the chemical and physical modifications induced by laser irradiation of varnish samples (i.e. dammar, mastic, shellac, mastic-oil) after natural and artificial ageing by using confocal ¿-Raman and laser induced fluorescence spectroscopies. We irradiated the varnish films with the fifth (213 nm) and fourth (266 nm) harmonics of a pulsed nanosecond (15 ns) Q-switched Nd:YAG laser. Together with systematic microscopy inspection of the irradiated areas, a significant effort was devoted to the study of the optical properties of the varnish films by means of UV-Vis absorption spectroscopy, which allowed the determination of linear absorption coefficients at the laser irradiation wavelengths used. Single-pulse laser ablation thresholds were measured by applying the spot regression method and processing of the films was carried out using three different scanning speeds that resulted in 1, 5 and 10 laser pulses on each irradiated area. The obtained results, using fluences well above the single-pulse ablation threshold of the treated varnishes, depend crucially on the irradiation wavelength, the considered varnish and its degree of polymerization. In contrast with the induced modifications resulting from irradiation at 266 nm, that lead to a whitish appearance (indicative of bubble formation) and discoloration of pigments, the promising results achieved at 213 nm emphasize the importance of using a highly absorbed wavelength to finely remove the oxidized uppermost layer of different types of aged varnishes. [1] Pouli, P., Paun, I. A., Bounos, G., Georgiou, S., Fotakis, C., Applied Surface Science, 254(21), 2008, 6875-6879. [2] Oujja, M., García, A., Romero, C., de Aldana, J. R. V., Moreno, P., Castillejo, M., Physical Chemistry Chemical Physics, 13(10), 2011, 4625-4631.Peer Reviewe

"Argento Deaurato" or "Argento Biancheggiato"? A Rare and Interesting Case of Silver Background in Italian Painting of the XIII Century

The painting depicting the "Virgin with the Child and two angels" by a Tuscan anonymous artist of the XIII century, has raised great interest regarding the execution technique including the use of silver, applied on wood as a background. An in-depth investigation was carried out especially concerning the burnishing process of the silver leaves as well as a detailed inspection of the nature of the organic compounds over the metal leaf and the degradation products of the silver layer. To this aim, a multianalytical approach was used including UV–VIS microscopy along with an Ultra-High-Resolution Scanning Electron Microscopy (UHR-SEM), as well as Fourier Transform Infrared (FTIR), fluorescence and micro-Raman spectroscopies. As a result, the presence of an oil-resin varnish layer in the uppermost layer and a wax-protein layer between the varnish and the metal layer as well as the evidence that the silver leaf was applied with high accuracy directly to the preparation layer, were clearly demonstrated. Furthermore, degradation products of the silver leaf were identified as sulphides, chlorides, and oxides. The holistic approach herein adopted enabled a step forward in the knowledge of the 13th century silver leaf gilding technique, adding value to the originality of this artwork. In this respect, the scientific evidence led to the assumption that likely this painting originally showed a silver-colored background ("argento biancheggiato") as compared to the initial theory of a case of "argento deaurato"

Spot‐on SERS Detection of Biomolecules with Laser‐Patterned Dot Arrays of Assembled Silver Nanowires

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Modern and ancient gold jewellery attributed to the Etruscans: a science-based study

A fibula with a lion and a pair of cluster earrings from the collection of the Florence National Museum of Archaeology, attributed to the Etruscans and said to originate from Populonia but suspected to be modern productions, were studied in the framework of the European project AUTHENTICO. They were compared to genuine objects from this same collection and from the collection of the National Museums Scotland. The study was carried out in situ in Florence with a stereomicroscope equipped with a digital camera, a handheld XRF spectrometer, and the portable LIPS prototype developed by AUTHENTICO. Some objects were studied with SEM and X-radiography. The aim of the study was to show that portable techniques of examination and analysis provide information on gold jewellery that allow the differentiation of modern and ancient productions.La fibule au lion et les boucles d’oreille à motifs floraux de la collection du musée national d’Archéologie de Florence, attribuées aux Étrusques, provenant de Populonia, mais suspectées d’être des productions modernes, ont été étudiées dans le cadre du projet européen AUTHENTICO et comparées à des objets originaux de cette même collection et de la collection des Musées Nationaux d’Écosse. L’étude a été réalisée in situ avec une loupe binoculaire équipée d’un appareil photo numérique, un analyseur de fluorescence X portable miniaturisé et le LIPS portable développé dans le cadre du projet AUTHENTICO. Certains objets ont été sélectionnés pour analyse au MEB et par radiographie. Le but de ce travail est de montrer que les informations obtenues grâce aux techniques portables d’examen et d’analyse permettent de différentier les productions modernes des anciennes

Casting cores used to craft large bronze masterpieces of the Florentine Renaissance and Mannerism

We investigated the casting cores of twelve large bronze masterpieces of the Florentine Renaissance and Mannerism (artworks by Ghiberti, Donatello, Verrocchio, Rustici, and Danti). Materials were characterized in their mineralogical-petrographic features, chemical composition, organic content and fossil traces. The results achieved provide information on the main recipes employed for manufacturing the casting cores, which largely agree with written sources of the time, and shed light on the art foundry processes between the 15the16th centuries. The data collected point out a pronounced affinity of natural raw materials used in all the casting cores investigated, consisting in silty-sandy clays with a suitable natural fine-grained temper component. A large use of organic fibres and matters of both animal and vegetal origin and a minor use of gypsum in selected workshops (Rustici, Verrocchio) were highlighted. Textural analyses allowed gaining information on direct vs indirect methods of casting, while firing temperatures up to about 1000 C were estimated from mineralogical and microstructural observations. Despite the strong similarities, significant differences among the various samples analysed were pointed out, providing some initial analytical clues that suggest different practices in separate workshops. Finally, the whole petrographic, geochemical and paleontological data gave information on the provenance of the clayey raw materials. This work represents the first step of a systematic approach to the classification of the core materials used in Florentine foundries along the centuries and shows the significant contribution the petrographic analyses can provide to the interpretation of the execution processes of large bronzes

L’ Istituto di Fisica Applicata “Nello Carrara”

The Institute of Applied Physics "Nello Carrara" (IFAC) of CNR in Florence has matured historically a strong tradition and continues to play a leading role in the introduction and testing of new technologies for the study and conservation of works of art , applied to sculptures and paintings (eg. by Michelangelo, Donatello and Masaccio) and monuments of inestimable historical and artistic value (eg. the Colosseum, the House of Augustus), in collaboration with major national restoration centers. Currently IFAC develop integrated spectroscopy techniques in the UV-Vis-IR and THz-GHz ranges for the study of the constituent materials and the state of conservation of cultural heritage. The research focuses on devices for non-invasive and in situ characterization of materials and for imaging, as well as on procedures of multivariate analysis of spectral data. Remote sensing techniques based on fluorescence LIDAR were applied for the first time in the survey of monuments by IFAC. Advanced diagnostic, such as LIPS (laser induced plasma spectroscopy) and 3D microscopy were originally developed for archeometric studies. In the field of restoration, IFAC has been a pioneer in the development of laser systems for cleaning of works of art made in stone, metal and painted surfaces, transferring these technologies to the Italian industry, which has become a world leader