An Ultrasonic Technique for Sizing Surface Cracks

Rayleigh surface waves are proposed as a non-destructive method to find the depth of surface cracks. The paper describes how dynamic photoelasticity was used to develop an understanding of the subsurface interactions between R-waves and a narrow slot. A frequency analysis of the transmitted wave confirmed that the slot acts as a low pass filter for the high frequency Fourier components of the input wave. It is then shown that the high frequency cut-off in the spectrum of the transmitted wave from broadband ultrasonic surface pulse can be used to determine the depth of surface slots

The isotropic correlation function of plane figures: the triangle case

The knowledge of the isotropic correlation function of a plane figure is useful to determine the correlation function of the cylinders having the plane figure as right-section and a given height as well as to analyze the out of plane intensity collected in grazing incidence small-angle scattering from a film formed by a particulate collection of these cylinders. The correlation function of plane polygons can always be determined in closed algebraic form. Here we report its analytic expression for the case of a triangle. The expressions take four different forms that depend on the relative order among the sides and the heights of the triangle.Comment: 11 pages, 2 figure

Ripening-related gene expression during fruit ripening in Vitis vinifera L. cv. Cabernet Sauvignon and Clairette blanche

The gene expression patterns in ripening fruit of a high quality wine cultivar (Cabernet Sauvignon) and a poor quality wine cultivar (Clairette blanche) were studied using cDNA-AFLP fingerprinting. Total RNA from "immature" (14-weeks post flowering) and "mature" (18-weeks post flowering) berries were used to study ripening-related gene expression in post-véraison stages of berry development. A total of 1,276 fragments were analysed, of which 175 appeared to be ripening-related. Average pairwise differences of the fragments amplified from "immature" and "mature" Cabernet Sauvignon and Clairette blanche berries, revealed a high level of similarity between the two cultivars. 70 % of the ripening-related fragments were cultivar-specific. The number of cultivar-specific and/or ripening-related fragments amplified, depended on the selective nucleotides of the primers used in the cDNA-AFLP analysis. Reverse slot blot and northern blot analysis confirmed that the expression of the identified genes were ripening-related.

Numerical Investigation of Light Scattering off Split-Ring Resonators

Recently, split ring-resonators (SRR's) have been realized experimentally in the near infrared (NIR) and optical regime. In this contribution we numerically investigate light propagation through an array of metallic SRR's in the NIR and optical regime and compare our results to experimental results. We find numerical solutions to the time-harmonic Maxwell's equations by using advanced finite-element-methods (FEM). The geometry of the problem is discretized with unstructured tetrahedral meshes. Higher order, vectorial elements (edge elements) are used as ansatz functions. Transparent boundary conditions and periodic boundary conditions are implemented, which allow to treat light scattering problems off periodic structures. This simulation tool enables us to obtain transmission and reflection spectra of plane waves which are incident onto the SRR array under arbitrary angles of incidence, with arbitrary polarization, and with arbitrary wavelength-dependencies of the permittivity tensor. We compare the computed spectra to experimental results and investigate resonances of the system.Comment: 9 pages, 8 figures (see original publication for images with a better resolution

Combining Contrast Invariant L1 Data Fidelities with Nonlinear Spectral Image Decomposition

This paper focuses on multi-scale approaches for variational methods and corresponding gradient flows. Recently, for convex regularization functionals such as total variation, new theory and algorithms for nonlinear eigenvalue problems via nonlinear spectral decompositions have been developed. Those methods open new directions for advanced image filtering. However, for an effective use in image segmentation and shape decomposition, a clear interpretation of the spectral response regarding size and intensity scales is needed but lacking in current approaches. In this context, $L^1$ data fidelities are particularly helpful due to their interesting multi-scale properties such as contrast invariance. Hence, the novelty of this work is the combination of $L^1$-based multi-scale methods with nonlinear spectral decompositions. We compare $L^1$ with $L^2$ scale-space methods in view of spectral image representation and decomposition. We show that the contrast invariant multi-scale behavior of $L^1-TV$ promotes sparsity in the spectral response providing more informative decompositions. We provide a numerical method and analyze synthetic and biomedical images at which decomposition leads to improved segmentation.Comment: 13 pages, 7 figures, conference SSVM 201

Intravitreal bevacizumab for the treatment of macular oedema secondary to branch retinal vein occlusion

Purpose: To evaluate the effect of intravitreal bevacizumab (Avastin) injections on visual acuity (VA) and foveal retinal thickness in patients with macular oedema secondary to branch retinal vein occlusion.Methods: A prospective, non-comparative, consecutive, interventional case series of 34 patients. Patients received repeated intravitreal injections of 1.25 mg bevacizumab. Main outcome measures were VA (Snellen charts and ETDRS) and retinal thickness (optical coherence tomography measurements) in a follow-up period of 6 months.Results: Patients presented at a mean age of 69 years (range 44--86). Mean duration of symptoms was 40 weeks (range 1--300). Mean (SD) VA at baseline was 0.79 (0.39) logMAR, improving to 0.51 (0.34) logMAR at 6 months (p = 0.009). Mean number of letters on the ETDRS chart at baseline was 45.3 (19.0), improving to 60.6 (19.9) at 6 months (p = 0.003). Mean (SD) retinal thickness at baseline was 474 (120) \textgreekmm, declining to 316 (41) \textgreekmm at 6 months.Conclusion: Intravitreal injection of 1.25 mg bevacizumb appears to be an effective treatment option for branch retinal vein occlusion

Molecular analysis of fruit ripening: The identification of differentially expressed sequences in Vitis vinifera using cDNA-AFLP technology

Differential gene expression patterns were studied during the ripening process of grape berries (Vitis vinifera cv. Chardonnay). Thirty PstI + MseI primer combinations were used to generate 213 fragments that appeared to be differentially expressed of which 94 % were successfully re-amplified. Reverse northern dot-blot analysis indicated that 35 % of the fragments had similar gene expression profiles to cDNA-AFLPs regarding developmental-stage specificity. Northern blot analyses confirmed the tissue and/or developmental stage specific expression of three of these cDNA fragments. This work illustrates that developmentally regulated sequences can be identified from grape berry tissue using cDNA-AFLP technology