Adaptative ranked-order vectorial speckle filtering in polarimetric SAR images : Comparaison with a class of filters

Speckle appearing in synthetic aperture radar (SAR) images is generated by coherent processing of radar signals . It hampers perception and extraction of fine details in the image . That is why speckle reducing is necessary before images analysis . In this paper, we have studied and tested several linear and non linear vectorial methods (Novak, Lee, Russell) to remove speckle in SAR images. Russell's method has proved its efficiency and simplicity of implementation, it is not adaptive . So we have generalized Russell's method to make it adaptive by pixel . Adaptivity is based on the generalization of local scalar variation towards a case of a vectorial variation, on one hand, and on local and global statistic analysis of the latter, on the other hand . To evaluate the performance of a filtering method, we propose criteria that join the two qualities, smoothing and edge preservation . A comparative study with several vectorial filtering methods show that the proposed method provides the best results according to the proposed criteria.La présence du bruit de chatoiement multiplicatif (speckle) dans les images radar à ouverture synthétique (ROS), causé par la cohérence de l'onde radar, rend difficile la perception et l'extraction des détails fins qui s'y trouvent. C'est pourquoi, avant d'effectuer l'analyse d'image, le filtrage du speckle pour réduire son influence est un traitement nécessaire. Dans cet article, nous avons étudié et testé différentes méthodes de filtrage vectorielles linéaires et non linéaires (Novak, Lee, Russel) pour réduire le bruit de speckle du signal d'images ROS. Le filtrage d'ordre vectoriel de Russel semble intéressant par son efficacité et par la simplicité de sa mise en oeuvre. Néamoins, il présente l'inconvénient d'être non adaptatif. C'est pourquoi, en étendant ce filtrage, nous l'avons rendu adaptatif en fonction des caractéristiques du voisinage. Cette adaptativité s'appuie d'une part, sur la généralisation de la notion de coefficient de variation scalaire au cas vectoriel et d'autre part, sur l'analyse statistique locale et globale de ce dernier. Un critère global d'évaluation des performances des filtres est proposé. Il combine les deux caractéristiques antagonistes d'une méthode de filtrage, capacité de lissage dans les zones homogènes et préservation des contours. Une comparaison quantitative, selon le critère proposé, sur les méthodes de filtrage vectoriel, citées plus haut, montre l'intérêt de la méthode proposée

Optimal processings design for synthetic aperture radar

Synthetic aperture radar (SAR) is a microwave imagery system capable ofproducing high resolution images by processing properly data collected by a relatively small antenna. In this papet the bi-dimensionnal received signal, using spatial coordinates, is formulated. The image is reconstructed by a two- dimensionnal filtering operation . We propose a straightforward derivation for the coherent sommation method (or bock-projection of range responses) and the 2-D azimuth matched filtering . The image quality is determined by that of the ambiguity fonction. This latter is analyzed and optimized for two performance criteria. First, for a matched filter receiver (maximal signal-to-noise ratio receiver), the optimal waveform is shown ta be a non linear FM pulse which autocorrelationfunction is a Taylor . The optimal azmiuth weighting fonction is related to that of Taylor by a Fourier transform . Second, for a Wiener filter (least mean-squares receiver), we show that the optimal waveform is the firstprolate spheroidal fonction . The single-hit measurement of the scattering matrix by mean of two optimal orthogonal waves is discussed . Resolutions, SNR as well as ambiguities, are specified .Le radar à visée latérale et à ouverture synthétique est un système d'imagerie micro-onde capable de produire des images de très haute résolution des terrains, et ceci à partir d'un traitement approprié des signaux reçus par une antenne de faible dimension, Dans cet article, nous présentons la formulation exacte du signal reçu, ainsi que les traitements associés afin de former l'image. On met en évidence l'équivalence entre la méthode de la sommation cohérente et le filtrage adapté bidimensionnel en azimut. La qualité de l'image ainsi formée est déterminée par celle de la fonction d'ambiguït

Unsupervised vectorial Markov segmentation of polarimetric radar imaging

statistical image model is used for segmenting polarimetric synthetic aperture radar (SAR) data into regions of homogeneous polarimetric backscatter characteristics . A model for the conditional distribution of the polarimetric complex data is combined with a Markov random field representation for the distribution of the region labels, to obtain the a posteriori distribution. Optimal region labels of the data are those which maximize the a posteriori distribution of the region labels given the polarimetric complex data . Implementation of the MAP (Maximun A Posteriori) technique is accomplished either by the modified deterministic ICM (Iterative Conditional Modes) algorithm or by the stochastic SA (Simulated Annealing) algorithm . Unsupervised parameter estimation procedures are obtained either by the CMFMAP-NSO (unsupervised fuzzy partition - optimal number of classes) and CMF-NS or by SEM (Stochastic Estimation Maximization) algorithm . The CMFMAP-NSO algorithm performs well in situations of large variability of cluster shapes, and densities . Results, using fully polarimetric SAR forest data, obtained by the CMFMAP-NSO following by the ICM algorithm with a K_ distribution model are quite satisfactory .La segmentation des images ROS (Radar à Ouverture Synthétique) consiste à produire une partition de l'image initiale en classes possédant certaines caractéristiques d'homogénéité au sens de la rétrodiffusion. Elle se pose en préalable à la plupart des schémas d'interprétation et de décision. Parmi les différentes techniques de segmentation possibles, nous avons privilégié celles basées sur une modélisation markovienne. A cet effet, un modèle statistique des images ROS polarimétriques est utilisé pour les segmenter en classes homogènes ayant chacune des caractéristiques de rétrodiffusion similaires. Cette segmentation utilise l'estimateur MAP (Maximum A Posteriori) que nous avons implémenté soit par l'algorithme déterministe ICM Modifié (Iterative Conditional Modes), soit par l'algorithme stochastique RS (Recuit Simulé). L'estimateur MAP correspond à la maximisation de la probabilité a posteriori de l'image d'un champ d'étiquettes de segmentation conditionnellement à la mesure faite. Pour cela un champ aléatoire de Markov représentant la distribution des étiquettes des classes est combiné avec un modèle (distribution Gaussienne ou distribution-K) représentant la distribution des données polarimétriques pour chacune des classes données. L'estimation des paramètres du modèle est non supervisée. Elle est basée sur une partition non contextuelle de l'image initiale obtenue par un groupement multidimentionnel des vecteurs caractéristiques soit par les algorithmes CMFMAP-NSO (Centres Mobiles Flous Non Supervisée et Optimale) et CMF-NS, soit par la méthode MV (Maximum de Vraisemblance) implémentée par l'algorithme SEM (Stochastic Estimation Maximisation). Les résultats de partition initiale et de segmentation obtenus sur une image mono-vue polarimétrique de la forêt des Landes, démontrent l'aptitude de l'algorithme proposé CMFMLAP-NSO à fournir une partition de bonne qualité d'une part et la capacité de l'algorithme ICM à affiner cette partition et à produire une segmentation de meilleure qualité d'autre part

Sustainable development goal 2: improved targets and indicators for agriculture and food security

The pursuit of global food security and agricultural sustainability, the dual aim of the second Sustainable Development Goal (SDG-2), requires urgent and concerted action from developing and developed countries. This, in turn, depends on clear and universally applicable targets and indicators which are partially lacking. The novel and complex nature of the SDGs poses further challenges to their implementation on the ground, especially in the face of interlinkages across SDG objectives and scales. Here we review the existing SDG-2 indicators, propose improvements to facilitate their operationalization and illustrate their practical implementation in Nigeria, Brazil and the Netherlands. This exercise provides insights into the concrete actions needed to achieve SDG-2 across contrasting development contexts and highlights the challenges of addressing the links between targets and indicators within and beyond SDG-2. Ultimately, it underscores the need for integrated policies and reveals opportunities to leverage the fulfillment of SDG-2 worldwide

Randomized controlled field trial to assess the immunogenicity and safety of rift valley fever clone 13 vaccine in livestock

BACKGROUND:Although livestock vaccination is effective in preventing Rift Valley fever (RVF) epidemics, there are concerns about safety and effectiveness of the only commercially available RVF Smithburn vaccine. We conducted a randomized controlled field trial to evaluate the immunogenicity and safety of the new RVF Clone 13 vaccine, recently registered in South Africa. METHODS:In a blinded randomized controlled field trial, 404 animals (85 cattle, 168 sheep, and 151 goats) in three farms in Kenya were divided into three groups. Group A included males and non-pregnant females that were randomized and assigned to two groups; one vaccinated with RVF Clone 13 and the other given placebo. Groups B included animals in 1st half of pregnancy, and group C animals in 2nd half of pregnancy, which were also randomized and either vaccinated and given placebo. Animals were monitored for one year and virus antibodies titers assessed on days 14, 28, 56, 183 and 365. RESULTS:In vaccinated goats (N = 72), 72% developed anti-RVF virus IgM antibodies and 97% neutralizing IgG antibodies. In vaccinated sheep (N = 77), 84% developed IgM and 91% neutralizing IgG antibodies. Vaccinated cattle (N = 42) did not develop IgM antibodies but 67% developed neutralizing IgG antibodies. At day 14 post-vaccination, the odds of being seropositive for IgG in the vaccine group was 3.6 (95% CI, 1.5 - 9.2) in cattle, 90.0 (95% CI, 25.1 - 579.2) in goats, and 40.0 (95% CI, 16.5 - 110.5) in sheep. Abortion was observed in one vaccinated goat but histopathologic analysis did not indicate RVF virus infection. There was no evidence of teratogenicity in vaccinated or placebo animals. CONCLUSIONS:The results suggest RVF Clone 13 vaccine is safe to use and has high (>90%) immunogenicity in sheep and goats but moderate (> 65%) immunogenicity in cattle

Chemical Library Screening and Structure-Function Relationship Studies Identify Bisacodyl as a Potent and Selective Cytotoxic Agent Towards Quiescent Human Glioblastoma Tumor Stem-Like Cells

Cancer stem-like cells reside in hypoxic and slightly acidic tumor niches. Such microenvironments favor more aggressive undifferentiated phenotypes and a slow growing "quiescent state" which preserves them from chemotherapeutic agents that essentially target proliferating cells. Our objective was to identify compounds active on glioblastoma stem-like cells, including under conditions that mimick those found in vivo within this most severe and incurable form of brain malignancy. We screened the Prestwick Library to identify cytotoxic compounds towards glioblastoma stem-like cells, either in a proliferating state or in more slow-growing "quiescent" phenotype resulting from non-renewal of the culture medium in vitro. Compound effects were assessed by ATP-level determination using a cell-based assay. Twenty active molecules belonging to different pharmacological classes have thus been identified. Among those, the stimulant laxative drug bisacodyl was the sole to inhibit in a potent and specific manner the survival of quiescent glioblastoma stem-like cells. Subsequent structure-function relationship studies led to identification of 4,4'-dihydroxydiphenyl-2-pyridyl-methane (DDPM), the deacetylated form of bisacodyl, as the pharmacophore. To our knowledge, bisacodyl is currently the only known compound targeting glioblastoma cancer stem-like cells in their quiescent, more resistant state. Due to its known non-toxicity in humans, bisacodyl appears as a new potential anti-tumor agent that may, in association with classical chemotherapeutic compounds, participate in tumor eradication

Pre-Clinical Evaluation of a Novel Nanoemulsion-Based Hepatitis B Mucosal Vaccine

Hepatitis B virus infection remains an important global health concern despite the availability of safe and effective prophylactic vaccines. Limitations to these vaccines include requirement for refrigeration and three immunizations thereby restricting use in the developing world. A new nasal hepatitis B vaccine composed of recombinant hepatitis B surface antigen (HBsAg) in a novel nanoemulsion (NE) adjuvant (HBsAg-NE) could be effective with fewer administrations.Physical characterization indicated that HBsAg-NE consists of uniform lipid droplets (349+/-17 nm) associated with HBsAg through electrostatic and hydrophobic interactions. Immunogenicity of HBsAg-NE vaccine was evaluated in mice, rats and guinea pigs. Animals immunized intranasally developed robust and sustained systemic IgG, mucosal IgA and strong antigen-specific cellular immune responses. Serum IgG reached > or = 10(6) titers and was comparable to intramuscular vaccination with alum-adjuvanted vaccine (HBsAg-Alu). Normalization showed that HBsAg-NE vaccination correlates with a protective immunity equivalent or greater than 1000 IU/ml. Th1 polarized immune response was indicated by IFN-gamma and TNF-alpha cytokine production and elevated levels of IgG(2) subclass of HBsAg-specific antibodies. The vaccine retains full immunogenicity for a year at 4 degrees C, 6 months at 25 degrees C and 6 weeks at 40 degrees C. Comprehensive pre-clinical toxicology evaluation demonstrated that HBsAg-NE vaccine is safe and well tolerated in multiple animal models.Our results suggest that needle-free nasal immunization with HBsAg-NE could be a safe and effective hepatitis B vaccine, or provide an alternative booster administration for the parenteral hepatitis B vaccines. This vaccine induces a Th1 associated cellular immunity and also may provide therapeutic benefit to patients with chronic hepatitis B infection who lack cellular immune responses to adequately control viral replication. Long-term stability of this vaccine formulation at elevated temperatures suggests a direct advantage in the field, since potential excursions from cold chain maintenance could be tolerated without a loss in therapeutic efficacy