Advances in multispectral and hyperspectral imaging for archaeology and art conservation

Multispectral imaging has been applied to the field of art conservation and art history since the early 1990s. It is attractive as a noninvasive imaging technique because it is fast and hence capable of imaging large areas of an object giving both spatial and spectral information. This paper gives an overview of the different instrumental designs, image processing techniques and various applications of multispectral and hyperspectral imaging to art conservation, art history and archaeology. Recent advances in the development of remote and versatile multispectral and hyperspectral imaging as well as techniques in pigment identification will be presented. Future prospects including combination of spectral imaging with other noninvasive imaging and analytical techniques will be discussed

Self-organization and optical response of silver nanoparticles dispersed in a dielectric matrix

Abstract. Double ion-beam sputtering has been used to fabricate nanocermet multilayers consisting of silver nanoparticles sandwiched between Si 3 N 4 dielectric layers. The organization of the nanoparticles has been studied in detail by quantitative analysis of transmission electronic microscopy and atomic force microscopy images. Our results show that the nanoparticles deposited on a plane surface present an isotropic macroscopic in-plane organization while their vertical arrangement displays a topology-induced self-organization. The use of faceted alumina substrates with periodic hill-and-valley structures results in the formation of linear chains of silver particles along the valleys. In that case, transmission optical measurements reveal in-plane anisotropy

Cardiac Hypertrophy Involves Both Myocyte Hypertrophy and Hyperplasia in Anemic Zebrafish

Background: An adult zebrafish heart possesses a high capacity of regeneration. However, it has been unclear whether and how myocyte hyperplasia contributes to cardiac remodeling in response to biomechanical stress and whether myocyte hypertrophy exists in the zebrafish. To address these questions, we characterized the zebrafish mutant tr265/tr265, whose Band 3 mutation disrupts erythrocyte formation and results in anemia. Although Band 3 does not express and function in the heart, the chronic anemia imposes a sequential biomechanical stress towards the heart. Methodology/principal findings: Hearts of the tr265/tr265 Danio rerio mutant become larger than those of the sibling by week 4 post fertilization and gradually exhibit characteristics of human cardiomyopathy, such as muscular disarray, re-activated fetal gene expression, and severe arrhythmia. At the cellular level, we found both increased individual cardiomyocyte size and increased myocyte proliferation can be detected in week 4 to week 12 tr265/tr265 fish. Interestingly, all tr265/tr265 fish that survive after week-12 have many more cardiomyocytes of smaller size than those in the sibling, suggesting that myocyte hyperplasia allows the long-term survival of these fish. We also show the cardiac hypertrophy process can be recapitulated in wild-type fish using the anemia-inducing drug phenylhydrazine (PHZ). Conclusions/significance: The anemia-induced cardiac hypertrophy models reported here are the first adult zebrafish cardiac hypertrophy models characterized. Unlike mammalian models, both cardiomyocyte hypertrophy and hyperplasia contribute to the cardiac remodeling process in these models, thus allowing the effects of cardiomyocyte hyperplasia on cardiac remodeling to be studied. However, since anemia can induce effects on the heart other than biomechanical, non-anemic zebrafish cardiac hypertrophy models shall be generated and characterized

Separation between the different fluxes scattered by art glazes: explanation of the special color saturation

International audienceIn a previous paper, the special visual appearance of art glazes was explained using the auxiliary function method (AFM) for solving the radiative transfer equation. Glazes are made of low concentrated colored scattering centers embedded in a transparent medium and the artist modulates the color by varying the number of glaze layers. A simple model of glazes and the new solving method have both been validated by comparison between flux measurements and modeling. The color of art glazes is analyzed here, and the study shows a spectacular maximum of saturation (purity) of the color that is never reached, to the best of our knowledge, with other techniques, such as pigment mixtures. This phenomenon is explained once more using the AFM that allows separation of the different contributions to the scattered fluxes. It is then shown that, on the one hand, single scattering never induces a maximum of saturation. On the other hand, multiple scattering has a typical increasing and decreasing behavior with an increasing number of glaze layers and thus participates to the maximum of saturation, just as the scattering by the diffuse base layer. A comparison between glazes and pigment mixtures, where the proportion of colored pigments with white pigments varies instead of the number of layers, shows that this maximum of saturation is much smaller with the second technique. To the best of our knowledge, we present a new development of the AFM that allows separation of the different origins of light scattering. We also show that it is possible to determine the optical properties of the scattering centers and of the base layer to create the required visual effect of a scattering medium. (c) 2006 Optical Society of America