Recent Results on the Extension Problem of Analytic Objects

We deal with the general problem of extension of analytic objects in a complex space X. After a short presentation of the classical results we discuss some recent developments obtained when X is a semi-1-corona. Semi-1-coronae are domains C ₊ whose boundary is the union of a Levi flat part, a 1-pseudoconvex part and a 1-pseudoconcave part. Using the main result in [31], we prove a “bump lemma” for compact semi-1-coronae in and then, applying Andreotti-Grauert theory, we get a cohomology finiteness theorem for coherent sheaves whose depth is at least 3. As an application we get an extension theorem for coherent sheaves and analytic subsets. Received: April 2007     

The Airy transform and associated polynomials

The Airy transform is an ideally suited tool to treat problems in classical and quantum optics. Even though the relevant mathematical aspects have been thoroughly investigated, the possibilities it offers are wide and some features, such as the link with special functions and polynomials, still contain unexplored aspects. In this note we will show that the so called Airy polynomials are essentially the third order Hermite polynomials. We will also prove that this identification opens the possibility of developing new conjectures on the properties of this family of polynomials.     

Digital holographic microscopy characterization of superdirective beam by metamaterial

Digital holographic microscopy (DHM) has been successfully applied for the first time to characterize the radiative out-of-plane emission properties of a superdirective device. Complementarily to near-field microscopy, DHM allows us to reconstruct the beam in the far-field region. The angular dispersion of the light beam radiated from a grating composed of air and anti-air metamaterial has been determined, and the proposed technique has highlighted a collimation degree higher than 0.04°, as already evaluated in a previous work. Further considerations on the retrieved phase map of the beam in the acquisition plane are presented.     

Chemical shift anisotropy amplification

A new NMR experiment which allows a measurement of the chemical shift anisotropy (CSA) tensor under magic angle spinning (MAS) is described. This correlates a fast MAS spectrum in the omega2 dimension with a sideband pattern in omega1 in which the intensities mimic those for a sample spinning at a fraction of the rate omega r/N, and these sidebands result from an amplification by a factor N of the modulation caused by the CSA. Standard methods can be used to extract the principal tensor components from the omega1 sideband patterns, and the nature of the experiment is such that the use of a large number of t1 increments can be avoided without compromising the resolution of different chemical sites. The new experiment is useful for accurately measuring narrow shift anisotropies.     

Modelling the soundscape quality of urban waterfronts by artificial neural networks

The renewal of the urban waterfronts has become a major focus of attention for politicians and decision makers in the city’s management programs. The recognition of the patterns that define the waterfronts’ identity is essential to select new strategies of intervention for the environmental recovery. In order to create adequate environments for everyday life within a sustainable development, new links between human senses, human perception and design need to be created. Within this wide approach, the landscape and the soundscape play a significant role and can become a key driving force in the implementation of the changes. New techniques have to be tested to identify the sonic and visual parameters capable to explain the specificity of a waterfront. With this purpose, an artificial neural network (ANN) was developed, and the relative importance of the input variables was evaluated. The collected database was also analysed by multiple linear regression (MLR) to compare the outcomes of both models. The urban waterfront of Naples (Italy) was chosen as case study. The results obtained show that the performance of the neural network is better than the one of the linear regression (rANN = 0.949, rMLR = 0.639). The interpretation of the relative importance method is also quite satisfactory in the ANN.     

Solid-State 1H-NMR Relaxation Properties of the Fruit of a Wild Relative of Eggplant at Different Proton Larmor Frequencies

¹H longitudinal relaxation time profiles (T1) at different proton Larmor frequencies were registered for a solid-state plant tissue by using fast field cycling (FFC) nuclear magnetic resonance (NMR) spectroscopy. T1 distributions were obtained and the curves deconvoluted in order to differentiate among the different T1 components. Among the components, two were assigned to hydrophobic (e.g., fatty acid) and hydrophilic (e.g., saccharide) molecular systems, whereas the others were attributed to bulk and bound water. This paper shows for the first time solid-state FFC-NMR spectroscopy applied to plant tissue and reveals that relaxometry is a very promising technique for studying plant systems.     

A combined analytical approach applied to Medieval wall paintings from Puglia (Italy): The study of painting techniques and its conservation state

A combined analytical approach has been applied to the wall paintings, dated from 10th to 14th centuries, of the Santi Stefani crypt at Vaste (Lecce, Southern Italy). These paintings are a precious testimony of Medieval art in Southern Italy. However, the church shows problems of damp as well as clear evidences of flora, fungi and mold presence, and there is little knowledge of the pictorial methodologies used. Raman spectroscopy allowed to determine the palette and to reconstruct the worksite and the chronological sequence of the various paint layers. Kaolinite, calcite, carbon black, hematite, massicot, goethite, indigo and azurite were identified as pigments along with synthetic pigments, like phthalocyanine blue and chrome yellow. Attenuated total reflectance‐Fourier transform infrared spectroscopy suggested the presence of egg as a binder in some pictorial layers. The conservation state of the crypt is poor, and detachments of pigmented layers are frequent because of the presence of subflorescence and efflorescence: nitrate, sulfate and chloride salts have been identified spectroscopically and quantified by ion chromatography. The extensive use of kaolinite in Santi Stefani, actually not uncommon in Medieval art, is observed for the first time in a crypt of Puglia: its use to stabilize some pigments and to improve their adhesion on substrate is proposed. Copyright © 2015 John Wiley & Sons, Ltd.     

Optimizing ICA in fMRI using information on spatial regularities of the sources

Spatial independent component analysis (ICA) is a well-established technique for multivariate analysis of functional magnetic resonance imaging (fMRI) data. It blindly extracts spatiotemporal patterns of neural activity from functional measurements by seeking for sources that are maximally independent. Additional information on one or more sources (e.g., spatial regularity) is often available; however, it is not considered while looking for independent components. In the present work, we propose a new ICA algorithm based on the optimization of an objective function that accounts for both independence and other information on the sources or on the mixing model in a very general fashion. In particular, we apply this approach to fMRI data analysis and illustrate, by means of simulations, how inclusion of a spatial regularity term helps to recover the sources more effectively than with conventional ICA. The improvement is especially evident in high noise situations. Furthermore we employ the same approach on data sets from a complex mental imagery experiment, showing that consistency and physiological plausibility of relatively weak components are improved.     

Superheating of silicon nanocrystals observed by Raman spectroscopy

In the Raman spectra of silicon nanocrystals a new anomalous component was detected. Close to the usual first order Raman peak situated for a bulk crystal at 521 cm⁻¹ at room temperature, two peaks arise shifting towards lower energy and demonstrating a huge temperature increase, as measured by the ratio of the Stokes/anti-Stokes peak intensities. This behavior is dependent on the laser power and on the morphology of the nanocrystals. We can exclude, however, confinement effects, although surface enhanced phonon modes could be responsible of such superheating. Alternative explanations are also suggested and discussed.     

Laboratory tests addressed to realize customized restoration procedures of underwater archaeological ceramic finds

The present contribution is part of a biennial research project funded by the Italian Ministry of Education, Universities and Research (MIUR). This study, currently in progress, deals with innovative experimental approaches applied to the chemical, mineralogical and physical transformations occurring during the prolonged permanence of archaeological ceramic finds in seawater environments as well as to restoration and conservation issues of the same underwater artifacts. The experimental approach used in this research consisted in the manufacture of ceramic test-pieces (briquettes) and their successive placing in underwater environment. This work aims at assessing how textural and compositional parameters along with firing temperatures of a ceramic paste could affect total porosity, pore size distribution and kinetics of capillary water absorption. A further purpose is concerned with the study of the potential modification of porosity and pore size distribution in the same ceramic bodies after immersion in seawater (3 and 6 months). The study was carried out using a multi-technique approach including investigations through polarized light microscopy (PLM), capillary water absorption test, mercury intrusion porosimetry (MIP) analyses and theoretical calculation of salt crystallization pressures. The obtained results show a different behavior of the six experimental pastes as a function of their compositional and textural features as well as pore size distribution and firing temperatures. These parameters, in various extents, have been found significantly influencing the kinetics of water absorption and the susceptibility of ceramic artifacts to salt crystallization processes, with important implications on conservation procedures needed before the musealization.