SAR amplitude probability density function estimation based on a generalized Gaussian model.

In the context of remotely sensed data analysis, an important problem is the development of accurate models for the statistics of the pixel intensities. Focusing on synthetic aperture radar (SAR) data, this modeling process turns out to be a crucial task, for instance, for classification or for denoising purposes. In this paper, an innovative parametric estimation methodology for SAR amplitude data is proposed that adopts a generalized Gaussian (GG) model for the complex SAR backscattered signal. A closed-form expression for the corresponding amplitude probability density function (PDF) is derived and a specific parameter estimation algorithm is developed in order to deal with the proposed model. Specifically, the recently proposed "method-of-log-cumulants" (MoLC) is applied, which stems from the adoption of the Mellin transform (instead of the usual Fourier transform) in the computation of characteristic functions and from the corresponding generalization of the concepts of moment and cumulant. For the developed GG-based amplitude model, the resulting MoLC estimates turn out to be numerically feasible and are also analytically proved to be consistent. The proposed parametric approach was validated by using several real ERS-1, XSAR, E-SAR, and NASA/JPL airborne SAR images, and the experimental results prove that the method models the amplitude PDF better than several previously proposed parametric models for backscattering phenomena.     

Exploring the Protein Stability Landscape: Bacillus subtilis Lipase A as a Model for Detergent Tolerance

A systematic study was conducted with Bacillus subtilis lipase A (BSLA) to determine the effect of every single amino acid substitution on detergent tolerance. BSLA is a minimal α/β‐hydrolase of 181 amino acids with a known crystal structure. It can be expressed in Escherichia coli and is biochemically well characterized. Site saturation mutagenesis resulted in a library of 3439 variants, each with a single amino acid exchange as confirmed by DNA sequencing. The library was tested against four detergents, namely SDS, CTAB, Tween 80, and sulfobetaine. Surface remodeling emerged as an effective engineering strategy to increase tolerance towards detergents. Amino acid residues that significantly affect the tolerance for each of the four detergents were identified. In summary, this systematic analysis provides an experimental dataset to help derive novel protein engineering strategies as well as to direct modeling efforts.     

Bilayer films composed of wheat gluten film and UV-cured coating: water vapor permeability and other functional properties

Summary Two types of UV-cured coating were deposited on wheat gluten film to improve the water vapor barrier properties of this highly interesting natural film in such application as fresh produces packaging. The use of an epoxy acrylate and an urethane acrylate coating allowed to reduce by half the water solubility and the water vapor permeance of the gluten film. Concerning the mechanical properties, the new bilayer films were more resistant but less resilient and flexible than the control gluten film. But the good adhesion between each UV coating and the gluten film increased the interest for these original materials. Received: 9 July 1999/Revised version: 24 March 2000/Accepted: 24 March 2000     

Sensory characteristics of spoilage and volatile compounds associated with bacteria isolated from cooked and peeled tropical shrimps using SPME-GC-MS analysis

The spoilage potential of six bacterial species isolated from cooked and peeled tropical shrimps (Brochothrix thermosphacta, Serratia liquefaciens-like, Carnobacterium maltaromaticum, Carnobacterium divergens, Carnobacterium alterfunditum-like and Vagococcus penaei sp. nov.) was evaluated. The bacteria were inoculated into shrimps, packaged in a modified atmosphere and stored for 27 days at 8 °C. Twice a week, microbial growth, as well as chemical and sensory changes, were monitored during the storage period. The bacteria mainly involved in shrimp spoilage were B. thermosphacta, S. liquefaciens-like and C. maltaromaticum whose main characteristic odours were cheese-sour, cabbage-amine and cheese-sour-butter, respectively. The volatile fraction of the inoculated shrimp samples was analysed by solid-phase microextraction (SPME) and gas chromatography coupled to mass spectrometry (GC-MS). This method showed that the characteristic odours were most likely induced by the production of volatile compounds such as 3-methyl-1-butanal, 2,3-butanedione, 2-methyl-1-butanal, 2,3-heptanedione and trimethylamine.     

Sub-pixel Bayesian estimation of albedo and height

Given a set of low resolution camera images of a Lambertian surface, it is possible to reconstruct high resolution luminance and height information, when the relative displacements of the image frames are known. We have proposed iterative algorithms for recovering high resolution albedo with the knowledge of high resolution height and vice versa. The problem of surface reconstruction has been tackled in a Bayesian framework and has been formulated as one of minimizing an error function. Markov Random Fields (MRF) have been employed to characterize the a priori constraints on the solution space. As for the surface height, we have attempted a direct computation without refering to surface orientations, while increasing the resolution by camera jittering.This project was partially supported by AFIRST (l'Association Franco-Israelienne pour la Recherche en Science et en Technologie).     

The effects of heat–moisture treatment of rice grains before parboiling on viscosity profile and physicochemical properties

The effects of heat–moisture treatment (HMT) (120 °C for 10, 30 and 60 min) on paddy rice grains before parboiling, on head rice yield (HRY), pasting and thermal properties, and colour and cooking characteristics of parboiled rice were studied. The results indicated that the HMT performed intensifies the changes in grains after parboiling, impacting pasting and thermal properties, which results in rice kernels with yellowish colouration and greater cooking time. HMT increased the temperatures of gelatinisation, with increasing HMT time from 10 to 60 min and reduced the gelatinisation enthalpy. HMT also affected the pasting properties of rice flours, reducing setback and viscosity and increased their stability to heat and mechanical agitation. The HMT performed in rice grains before the parboiling process with 60 min of the treatment decreased the HRY and increased the level of metabolic defects only in the treatment with 60 min.     

Extended Phase Field Higher-Order Active Contour Models for Networks

This paper addresses the segmentation from an image of entities that have the form of a ‘network’, i.e. the region in the image corresponding to the entity is composed of branches joining together at junctions, e.g. road or vascular networks. We present new phase field higher-order active contour (HOAC) prior models for network regions, and apply them to the segmentation of road networks from very high resolution satellite images. This is a hard problem for two reasons. First, the images are complex, with much ‘noise’ in the road region due to cars, road markings, etc., while the background is very varied, containing many features that are locally similar to roads. Second, network regions are complex to model, because they may have arbitrary topology. In particular, we address a limitation of a previous model in which network branch width was constrained to be similar to maximum network branch radius of curvature, thereby providing a poor model of networks with straight narrow branches or highly curved, wide branches. We solve this problem by introducing first an additional nonlinear nonlocal HOAC term, and then an additional linear nonlocal HOAC term to improve the computational speed. Both terms allow separate control of branch width and branch curvature, and furnish better prolongation for the same width, but the linear term has several advantages: it is more efficient, and it is able to model multiple widths simultaneously. To cope with the difficulty of parameter selection for these models, we perform a stability analysis of a long bar with a given width, and hence show how to choose the parameters of the energy functions. After adding a likelihood energy, we use both models to extract the road network quasi-automatically from pieces of a QuickBird image, and compare the results to other models in the literature. The state-of-the-art results obtained demonstrate the superiority of our new models, the importance of strong prior knowledge in general, and of the new terms in particular.     

Expansion Properties of Sour Cassava Starch (Polvilho Azedo): Variables Related to its Practical Application in Bakery

Sour cassava starch (polvilho azedo) is a chemically and enzymatically modified starch with the specific property of expansion in bakery products without the use of any chemical or biological leavening agents. In this work, the cumulative knowledge about sour cassava starch is presented in relation to its physicochemical characteristics, with the purpose of establishing a relation between the application properties and some structural and chemical characteristics in order to design a model of the modified structure of starch and the most important technical variables. Such approach will help to provide some quality standards for future adequate valorization of sour cassava starch, especially with respect to potential use in gluten‐free products. This work showed that a good sour cassava starch is significantly different from low expansion cassava starches with respect to pH, acid factor, swelling power, specific volume, and polymerization degree (intrinsic viscosity). These variables could be related to the maximization of sour cassava starch expansion for a future predictive decision analysis about a high quality sour cassava starch to the baking use.