Vehicle detection by means of stereo vision-based obstacles features extraction and monocular pattern analysis.

This paper presents a stereo vision system for the detection and distance computation of a preceding vehicle. It is divided in two major steps. Initially, a stereo vision-based algorithm is used to extract relevant three-dimensional (3-D) features in the scene, these features are investigated further in order to select the ones that belong to vertical objects only and not to the road or background. These 3-D vertical features are then used as a starting point for preceding vehicle detection; by using a symmetry operator, a match against a simplified model of a rear vehicle's shape is performed using a monocular vision-based approach that allows the identification of a preceding vehicle. In addition, using the 3-D information previously extracted, an accurate distance computation is performed.     

Biosorption performance,combustion behavior,and leaching characteristics of olive solid waste during the removal of copper and nickel from aqueous solutions

Several researchers have proved that agricultural by-products constitute good adsorbents for removing heavy metals from aqueous solution. However, few investigations have identified efficient strategies for the adsorbent′s regeneration. Hence, a global methodology for the removal of copper and nickel metals from wastewater including metal biosorption, thermal treatment and residual ash landfill is proposed. In order to validate this strategy, olive solid waste (OSW), provided by an olive oil mill from Tunisia, were used to remove copper and nickel on batch experiments. Copper and nickel were adsorbed on a monolayer of OSW surface with maximal adsorption capacity (q _max) of 3.6 and 1.7 mg g^?1, respectively. Contaminated OSW with copper and nickel were combusted at 850 °C in an electrical furnace. About 96 % of each metal was recovered in residual ashes that present a good secondary raw material for copper and nickel production. Low leaching transfers (≤4 %) were observed for copper and nickel from residual ashes leading to the possibility to be landfilled. Therefore, the suggested process can be used as an alternative to the classical technologies for effluent decontamination.     

Optimized transmission line matrix model implementation for graphics processing units computing in built-up environment

The increase in computational capabilities has made time-domain methods applicable for long-range sound propagation modelling. However, such approaches remain very demanding in terms of computational resources. Most current computers are supplied with a powerful device which is still little exploited: the graphics processing unit (GPU). The paper describes an implementation of a transmission line matrix model which allows parallel calculations on heterogeneous systems. A voxelization algorithm used to generate the computational domain is presented. A splitting process is also expounded which makes feasible performing huge domains simulations by accurately dividing the computational domain into subdomains. Each subdomain is enlarged by introducing extra cells containing neighbours subdomains data in order to run several computational iterations on a graphic device without data exchange with the system memory. The influence of the ghost layer depth and the speeding up of computation time with GPU are then illustrated in a realistic built-up area.     

Macroporous calcium phosphate ceramic implants for sustained drug delivery

Limited blood circulation to the skeletal tissue is a major cause of reduced therapeutic effects seen with drugs administered by conventional systemic ways. To resolve this issue and obtain a sufficiently high local concentration to induce therapeutic effects, several implanted drug delivery systems have been developed for hard tissues using biomaterials.We have designed a drug delivery device based on hydroxylapatite (HA) and tested it in vitro using metronidazol and chloramphenicol as model compounds. Porous HA ceramics were prepared with two different shapes (cylindrical and spherical). Known amounts of drugs were introduced inside a drilled hole and sealed with wax. The ceramics were then suspended in stirred distilled water in closed polypropylene vials. Drug release was observed during several weeks.A mathematical model used to describe drug release from HA was elaborated based on the expressions of Fick's laws. The experimental kinetic results could be related to ceramic constitution and to drug localization.     

Optical and physical properties of stratospheric aerosols from balloon measurements in the visible and near-infrared domains. 1. Analysis of aerosol extinction spectra from the AMON and SALOMON balloonborne spectrometers

Aerosol extinction coefficients have been derived in the 375-700-nm spectral domain from measurement in the stratosphere since 1992, at night, at mid- and high latitudes from 15 to 40 km, by two balloonborne spectrometers, Absorption par les Minoritaires Ozone et NO(chi) (AMON) and Spectroscopie d'Absorption Lunaire pour l'Observation des Minoritaires Ozone et NO(chi) (SALOMON). Log-normal size distributions associated with the Mie-computed extinction spectra that best fit the measurements permit calculation of integrated properties of the distributions. Although measured extinction spectra that correspond to background aerosols can be reproduced by the Mie scattering model by use of monomodal log-normal size distributions, each flight reveals some large discrepancies between measurement and theory at several altitudes. The agreement between measured and Mie-calculated extinction spectra is significantly improved by use of bimodal log-normal distributions. Nevertheless, neither monomodal nor bimodal distributions permit correct reproduction of some of the measured extinction shapes, especially for the 26 February 1997 AMON flight, which exhibited spectral behavior attributed to particles from a polar stratospheric cloud event.     

Influence of principal component analysis acceleration factor on velocity measurement in 2D and 4D PC-MRI

Objective

The objective of the study was to determine how to optimize 2D and 4D phase-contrast magnetic resonance imaging (PC-MRI) acquisitions to acquire flow velocities in millimetric vessels. In particular, we search for the best compromise between acquisition time and accuracy and assess the influence of the principal component analysis (PCA).

Materials and methods

2D and 4D PC-MRI measurements are conducted within two in vitro vessel phantoms: a Y-bifurcation phantom, the branches of which range from 2 to 5 mm in diameter, and a physiological subject-specific phantom of the carotid bifurcation. The same sequences are applied in vivo in carotid vasculature.

Results

For a vessel oriented in the axial direction, both 2D and axial 4D PC-MRI provided accuracy measurements regardless of the k-t PCA factor, while the acquisition time is reduced by a factor 6 for k-t PCA maximum value. The in vivo measurements show that the proposed sequences are adequate to acquire 2D and 4D velocity fields in millimetric vessels and with clinically realistic time durations.

Conclusion

The study shows the feasibility of conducting fast, high-resolution PC-MRI flow measurements in millimetric vessels and that it is worth maximizing the k-t PCA factor to reduce the acquisition time in the case of 2D and 4D axial acquisitions.

     

Optical and physical properties of stratospheric aerosols from balloon measurements in the visible and near-infrared domains. II. Comparison of extinction,reflectance, polarization,and counting measurements

The physical properties of stratospheric aerosols can be retrieved from optical measurements involving extinction, radiance, polarization, and counting. We present here the results of measurements from the balloonborne instruments AMON, SALOMON, and RADIBAL, and from the French Laboratoire de Météorologie Dynamique and the University of Wyoming balloonborne particle counters. A cross comparison of the measurements was made for observations of background aerosols conducted during the polar winters of February 1997 and January-February 2000 for various altitudes from 13 to 19 km. On the one band, the effective radius and the total amount of background aerosols derived from the various sets of data are similar and are in agreement with pre-Pinatubo values. On the other hand, strong discrepancies occur in the shapes of the bimodal size distributions obtained from analysis of the raw measurement of the various instruments. It seems then that the log-normal assumption cannot fully reproduce the size distribution of background aerosols. The effect ofthe presence of particular aerosols on the measurements is discussed, and a new strategy for observations is proposed.     

In vitro inhibition of Escherichia coli O157:H7 by bifidobacterial strains of human origin

The ability of bifidobacteria isolated from infant feces to inhibit enterohemorrhagic Escherichia coli serotype O157:H7 in vitro and reduce its adhesion to human enterocyte-like Caco-2 cells was evaluated in comparison to American Type Culture Collection bifidobacterial reference strains. Five Bifidobacterium isolates from infant feces were identified and characterized by morphology, fructose-6-phosphate phosphoketolase (F6PPK) assay, polymerase chain reaction using bifidobacterial 16S rDNA specific primers, carbohydrate fermentation patterns, resistance to lysozyme, acid, bile and hydrogen peroxide as well as their ability to inhibit E. coli O157:H7 using the agar spot technique. Infant isolates showed greater resistance to bile, acid, lysozyme and more antimicrobial activity against E. coli O157:H7 than ATCC strains. Two infant isolates identified as B. bifidum RBL 71 and B. bifidum RBL 460 showed good adhesion and significant potential for reducing adhesion of E. coli O157:H7 to Caco-2 cells. This effect was dependent on bifidobacterial cell concentration. These results show that bifidobacteria isolated from infants may be useful for improving probiotic formulae with respect to protection against E. coli O157:H7 infection.