Relevance feedback for CBIR: a new approach based on probabilistic feature weighting with positive and negative examples.

In content-based image retrieval, understanding the user's needs is a challenging task that requires integrating him in the process of retrieval. Relevance feedback (RF) has proven to be an effective tool for taking the user's judgement into account. In this paper, we present a new RF framework based on a feature selection algorithm that nicely combines the advantages of a probabilistic formulation with those of using both the positive example (PE) and the negative example (NE). Through interaction with the user, our algorithm learns the importance he assigns to image features, and then applies the results obtained to define similarity measures that correspond better to his judgement. The use of the NE allows images undesired by the user to be discarded, thereby improving retrieval accuracy. As for the probabilistic formulation of the problem, it presents a multitude of advantages and opens the door to more modeling possibilities that achieve a good feature selection. It makes it possible to cluster the query data into classes, choose the probability law that best models each class, model missing data, and support queries with multiple PE and/or NE classes. The basic principle of our algorithm is to assign more importance to features with a high likelihood and those which distinguish well between PE classes and NE classes. The proposed algorithm was validated separately and in image retrieval context, and the experiments show that it performs a good feature selection and contributes to improving retrieval effectiveness.     

New theoretical expressions for the five adsorption type isotherms classified by BET based on statistical physics treatment

New theoretical expressions to model the five adsorption isotherm types have been established. Using the grand canonical ensemble in statistical physics, we give an analytical expression to each of five physical adsorption isotherm types classified by Brunauer, Emett, and Teller, often called BET isotherms. The establishment of these expressions is based on statistical physics and theoretical considerations. This method allowed estimation of all the mathematical parameters in the models. The physicochemical parameters intervening in the adsorption process that the models present could be deduced directly from the experimental adsorption isotherms by numerical simulation. We determine the adequate model for each type of isotherm, which fixes by direct numerical simulation the monolayer, multilayer, or condensation character. New equations are discussed and results obtained are verified for experimental data from the literature. The new theoretical expressions that we have proposed, based on statistical physics treatment, are rather powerful to better understand and interpret the various five physical adsorption type isotherms at a microscopic level.     

Influence of the building material and ventilation rate on the concentration of radon, thoron and their progenies in dwelling rooms using SSNTD and Monte Carlo simulation

A new Monte Carlo computer code was developed for determining the detection efficiencies of the CR-39 and LR-115 II solid state nuclear track detectors (SSNTD) for a-particles emitted by radon (²²²Rn) and thoron (²²⁰Rn) series inside the atmosphere of dwelling rooms. Alpha-activities due to radon, thoron and their decay products, were evaluated for the determination of the detection efficiencies of the SSNTD utilized for the emitted a-particles by measuring the corresponding track densities. The influence of the ventilation rate and building material on the concentration of radon, thoron and their progenies was investigated. Equilibrium factors between radon and its progeny and between thoron and its daughters have been evaluated in the air of the rooms.     

Staphylococcus aureus bicomponent gamma-hemolysins, HlgA, HlgB, and HlgC, can form mixed pores containing all components

Staphylococcal gamma-hemolysins are bicomponent toxins forming a protein family with leucocidins and alpha-toxin. Two active toxins (AB and CB) can be formed combining one of the class-S components, HlgA or HlgC, with the class-F component HlgB. These two gamma-hemolysins form pores with marked similarities to alpha-toxin in terms of conductance, nonlinearity of the current-voltage curve, and channel stability in the open state. AB and CB pores, however, are cation-selective, whereas alpha-toxin is anion-selective. gamma-Hemolysins' pores are hetero-oligomers formed by three or four copies of each component (indicated as 3A3B and 3C3B or 4A4B and 4C4B). Point mutants located on a beta-strand of the class-S component that forms part of the protomer-protomer contact region can prevent oligomer assembly. Interestingly, these mutants inhibit growth of pores formed not only by their natural components but also by nonstandard components. This lead to the hypothesis that mixed ABC pores could also be formed. By studying the conductance of pores, assembled in the presence of all three components (in different ratios), it was observed that the magnitudes expected for mixed pores were, indeed, present. We conclude that the gamma-hemolysin/leucocidin bicomponent toxin family may form a larger than expected number of active toxins by cross-combining various S and F components.     

Synthese De (1,2a)Benzimidazolo-1,3,5,2-triazaphosphorine-2-oxides

The reaction of hexamethylphosphotriamide or methylphosphonic bis(dimethylamide) compounds with amidines derived from N-Benzimidazoyl imidates 1 leads to (1,2a)benzimidazolo-1,3,5,2-tiazaphosphorine-2-oxides 4 in good yields. If the condensation is realized at room temperature, N-phosphonic amidines 3 can be isolated as intermediates. The isolated compounds 2 , 3 , and 4 are identified by spectroscopic methods: IR, 1 H, 13 C, 31 P, NMR, and M.S.     

SYNTHESIS AND REACTVITY OF N-[N-PHOSPHORAMIDO-1H-BENZIMIDAZOL-2-YL] IMIDATES

N-(-1H-Benzimidazol-2-yl) imidates 1a–c react with chlorophosphoramide to give the N-[-1-N,N,N′,N′-tetramethylphosphoramidoyl-1H-benzimidazol-2-yl]-imidates 2a–c or with dichlorophosphoramide to yield the bis[(N-1-benzimidazol-2-yl)-imidate] phosphoramide derivatives 3a–b. The reaction of compounds 2a–c toward primary amines is studied. The obtained amidine derivatives 4a–b were unambiguously characterized by different spectroscopic techniques (IR, ¹H, ¹³C, and ³¹P NMR, and in some cases MS).     

Structural characterization and hydrogen sorption properties of the Mg50Ni45Cr5 alloy

The Mg₅₀Ni₄₅Cr₅ alloy for hydrogen storage is prepared by mechanical alloying. First, using the X-ray diffraction (XRD) and the scanning electron microscopy (SEM) we examine the morphology and the structure of the substrate. The obtained results highlight the effectiveness of this alloy in loading hydrogen as it is a nanocrystalline and a ductile one. Second, we attempt to justify these expectations using the statistical physic, precisely the model monolayer with two levels of energy, in modeling a hydrogen absorption and desorption isotherms on Mg₅₀Ni₄₅Cr₅ alloy at four temperatures T?=?275?K, T?=?300?K, T?=?325?K and T?=?350?K. The model has six physicochemical parameters deduced from the fitting of the isotherms, they are divided by two categories of steric and energetic parameters. Thanks to these parameters we compare the absorption and desorption processes, in order to highlight the hysteresis phenomenon encountered during the hydrogen sorption.     

NOUVELLE SYNTHÈSE DE [1,2-A]BENZIMIDAZOLO-1,3,5,2-TRIAZAPHOSPHORINES ET DE [1,2-A]BENZIMIDAZOLO-1,3,5,2- TRIAZAPHOSPHORINE-2-THIONES

The condensation of N₁-benzimidazolyl amidines 1 with tris(dimethy- lamino)phosphine leads to the corresponding [1,2a]Benzimidazolo-1,3,5,2-triazaphosphorines 3 . The N₂-phosphoroamidine intermediates 2′ are isolated and yielded the corresponding cyclic compounds 4 upon heating. The oxidation by sulfur of the compounds 3 gives the thiooxide derivatives 4 .

The structure of these compounds is unambiguously confirmed by IR, ¹H, ³¹P, and ¹³C NMR spectroscopy and by MS for some products.     

The Influence of the Calcination and Water Washing Treatments on the Uranium Content in Sedimentary Phosphate Samples Using Solid State Nuclear Track Detectors and Gamma-Ray Spectrometry

The uranium and thorium contents were evaluated in the 100–400 µm granulometric fraction of different sedimentary phosphate samples by using a method based on determining the mean critical angles of etching of the CR-39 and LR-115 type II solid state nuclear track detectors (SSNTD) for detecting -particles emitted by the nuclei of the uranium-238 and thorium-232 series. Data obtained were compared with the results of -ray spectrometry measurements performed on the same samples. The influence of the calcination and water washing treatments as well as the lithology and stratigraphy on the uranium concentration of the phosphate samples was investigated.     

Facile preparation of 3-substituted 2-quinazolinones via electrogenerated base

A new series of 3,4-disubstituted quinazolin-2-ones, with potential T-type calcium channel antagonist activity, and new 4-methylene-quinazolin-2-ones, promising catalysts as N-heterocyclic olefins, have been prepared in good yield by a simple reaction between 2-aminobenzophenone, or 2-aminoacetophenone, and cyanomethyl anion electrogenerated by acetonitrile reduction at a graphite electrode, followed by the addition of different organic isocyanates and subsequent heterocyclization.