New phospholipid fatty acids from the marine spongeCinachyrella alloclada uliczka

The fatty acid composition of phospholipids from the Senegalese spongeCinachyrella alloclada was examined. Two new fatty acids not hitherto found in nature, namely 10,13-octadecadienoic acid and 16-tricosenoic acid, were identified. 8-Hexadecenoic, 13-nonadecenoic and 5,9,13-trimethyltretradecanoic fatty acids were also found for the first time in sponges. The latter compound (1.4% of the total fatty acid mixture), an isoprenoid fatty acid, accompanies the major fatty acid 4,8,12-trimethyltridecanoic acid (19.7%). The monomethyl branched fatty acids (22%) identified include 23-methylpentacosanoic acid (anteiso-26∶0), not previously observed in sponged. The major long-chain fatty acids encountered were the known 17-tetracosenoic 19-heptacosadienoic and 5,9,23-tricontatrienoic acid. Some sixty fatty acids were identified as methyl esters andN-acyl pyrrolidides by gas chromatography and gas chromatography/mass spectrometry.     

In vitro comparison of hepatic metabolism of 9cis-11 trans and 10trans-12cis isomers of CLA in the rat

Hepatic metabolism of the two main isomers of CLA (9cis-11 trans, 10trans-12cisC_18∶2) was compared to that of oleic acid (representative of the main plasma FA) in 16 rats by using the in vitro method of incubated liver slices. Liver tissue samples were incubated at 37°C for 17h under an atmosphere of 95% O₂/5%CO₂ in a medium supplemented with 0.75 mM of FA mixture (representative of circulating nonesterified FA) and with 55 μM [1-¹⁴C]9cis-11 trans C_18∶2, [1-¹⁴C]10trans-12cis C_18∶2, or [1-¹⁴C]oleate. The uptake of CLA by hepatocytes was similar for both isomers (9%) and was three times higher (P<0.01) than for oleate (2.6%). The rate of CLA isomer oxidation was two times higher (49 and 40% of incorporated amounts of 9cis-11 trans and 10trans-12 cis, respectively) than that of oleate (P<0.01). Total oxidation of oleate and CLA isomers into [¹⁴CO₂] was low (2 to 7% of total oxidized FA) compared to the partial oxidation (93 to 98%) leading to the production of [¹⁴C] acid-soluble products. CLA isoemrs escaping from catabolism were both highly desaturated (26.7 and 26.8%) into conjugated 18∶3. Oleate and CLA isomers were mainly esterified into neutral lipids (30%). They were slowly secreted as parts of VLDL particles (<0.4% of FA incorporated into cells), the extent of secretion of oleate and of 10trans-12 cis being 2.2-fold higher than that of 9cis-11 trans (P<0.02). In conclusion, this study clearly showed that both CLA isomers were highly catabolized by hepatocytes, reducing their availability for peripheral tissues. Moreover, more than 25% of CLA escaping from catabolism was converted into conjugated 18∶3, the biological properties of which remain to be elucidated.     

Clinical trial results support a preference for using CLA preparations enriched with two isomers rather than four isomers in human studies

CLA mixtures are now commercially available. They differ from each other with respect to their content of CLA isomers and their degree of purification. As a group of natural FA, CLA have been widely assumed to be safe. However, the suspected presence of both impurities and particular isomers might induce undesirable side effects. Despite this potential health risk, only a few CLA preparations have been tested under rigorous conditions for clinical efficacy and safety. Based on the limited results available, it is possible to suggest that preparations enriched in c9,t11 and t10,c12 isomers are preferable for human consumption compared to preparations containing four isomers, in terms both of safety and efficacy.     

Behaviour based on decision matrices for a coordination between agents in a urban traffic simulation

This paper describes a multi-agent coordination mechanism applied to intersection simulation situations. In a goal of urban traffic simulation, we must consider the dynamic interactions between autonomous vehicles. The field of multi-agent systems provides us some studies for such systems, in particular on the coordination mechanisms. Conflicts between vehicles (i.e. agents) are very frequent in such applications, and they may cause deadlocks, particularly at intersections such as crossroads. Our approach is based on the solving of two player games/decision matrices which characterize three basic situations. An aggregation method generalizes to n-player games for complex crossroads. The objective of this approach consists in searching basic two-player matrices for solving n-agent problems. To explain the principle, we describe our approach for a particular case of crossroad with three agents. Finally, the obtained results have been examined via a tool of road traffic simulation, ARCHISIM. We assume also that the global traffic replicates the behavior of agents in different situations.     

Crossing textual and visual content in different application scenarios

This paper deals with multimedia information access. We propose two new approaches for hybrid text-image information processing that can be straightforwardly generalized to the more general multimodal scenario. Both approaches fall in the trans-media pseudo-relevance feedback category. Our first method proposes using a mixture model of the aggregate components, considering them as a single relevance concept. In our second approach, we define trans-media similarities as an aggregation of monomodal similarities between the elements of the aggregate and the new multimodal object. We also introduce the monomodal similarity measures for text and images that serve as basic components for both proposed trans-media similarities. We show how one can frame a large variety of problem in order to address them with the proposed techniques: image annotation or captioning, text illustration and multimedia retrieval and clustering. Finally, we present how these methods can be integrated in two applications: a travel blog assistant system and a tool for browsing the Wikipedia taking into account the multimedia nature of its content.

Cognitive control by brain-injured car drivers: an exploratory study

Cognitive control is a key tool for adaptation in dynamic situations. The aim of the study is to assess the relevance of a theoretical framework for cognitive control in dynamic situations, in order to understand brain-injured (BI) car drivers' cognitive impairment. The framework supports a cognitive control multimodality based on the crossing of two orthogonal dimensions: symbolic/subsymbolic; anticipative/reactive control. BI car drivers' behaviour was compared with that of a control group (CTRL) during driving simulator scenarios. Eye movement analysis, among other variables, revealed that BI car drivers made use of a more symbolic and reactive control than did CTRL drivers. CTRL drivers showed a more stable cognitive compromise than BI drivers. The latter became less symbolic and more reactive in the case of difficult scenarios. In addition, BI drivers focused on the main task of trajectory management, with fewer resources devoted to traffic interaction management. STATEMENT OF RELEVANCE: An explanation of differences between BI and CTRL drivers in terms of cognitive control requirements, attention and processing speed is put forward. From this, it is possible to derive some implications in terms of driver assistance (e.g. lane keeping or a warning assistance device) and rehabilitation.     

In-plane rigid-body vibration mode characterization with a nanometer resolution by stroboscopic imaging of a microstructured pattern

This article introduces an improved approach for the characterization of in-plane rigid-body vibration, based on digital processing of stroboscopic images of the moving part. The method involves a sample preparation step, in order to pattern a periodic microstructure on the vibrating device, for instance, by focused ion beam milling. An image processing method has then been developed to perform the optimum reconstruction of this a priori known object feature. In-plane displacement and rotation are deduced simultaneously with a high resolution (10-2 pixel and 0.5 x 10(-3) rad, respectively). The measurement principle combines phase measurements-that provide the high resolution-with correlation-that unwraps the phase with the proper phase constants. The vibration modes of a tuning fork are used for demonstrating the capabilities of the method. For applications allowing the sample preparation, the proposed methodology is more convenient than common interference methods or image processing techniques for the characterization of the vibration modes, even for amplitudes in the nanometer range.     

d-Dimensional parametric models for dynamic animation of deformable objects

This paper introduces an accurate, efficient, and unified engine dedicated to dynamic animation of d-dimensional deformable objects. The objects are modelled as d-dimensional manifolds defined as functional combinations of a mesh of 3D control points, weighted by parametric blending functions. This model ensures that, at each time step, the object shape conforms to its manifold definitions. The object motion is deduced from the control points dynamic animation. In fact, control points should be viewed as the degrees of freedom of the continuous object. The chosen dynamic equations (Lagrangian formalism) reflect this generic modelling scheme and yield an exact and computationally efficient linear system.     

Lyapunov exponential stability of 1-D linear hyperbolic systems of balance laws

Explicit boundary dissipative conditions are given for the exponential stability in $L^2$-norm of one-dimensional linear hyperbolic systems of balance laws ${?}_t\xi +\Lambda {?}_x\xi ?M\xi =0$ over a finite interval, when the matrix $M$ is marginally diagonally stable. The result is illustrated with an application to boundary feedback stabilisation of open channels represented by linearised Saint–Venant–Exner equations.     

Searching for information in an online public access catalogue (OPAC): the impacts of information search expertise on the use of Boolean operators

Abstract Boolean systems still constitute most of the installed base of online public access catalogues (OPACs) in the French universities even if many studies have shown that Boolean operators are not frequently used by ‘non‐librarian’ users (by contrast with professional librarians). The first study examined the use of Boolean operators by French university students; In the second study, elaborated to evaluate the impact of information search expertise on this use, Boolean operators are explicitly presented and participants were explicitly invited to use them. We assumed that university students would not frequently use the operators in searching, and that even if they were explicitly invited to make use of them. Results obtained with the first study based on transaction logs analyses confirmed that French university students did not frequently use Boolean operators. The impact of information search expertise, analysed in the second study, compared three levels of expertise: Novice (university students), intermediate (future professional librarians), and expert (professional librarians). Results showed that, even if the three groups were invited to use Boolean operators, this use increased significantly with the level of information search expertise. University students, if they manage procedural functions of connectives in natural language, do not always manage the whole set of procedural functions carried by such connectives when used in the documentary language. So, the relevance of presenting explicit Boolean operators in the OPACs when users are ‘non‐librarians’ is questioned.