Which persistent organic pollutants can we map in soil using a large spacing systematic soil monitoring design? A case study in Northern France

Persistent organic pollutants (POPs) impact upon human and animal health and the wider environment. It is important to determine where POPs are found and the spatial pattern of POP variation. The concentrations of 90 molecules which are members of four families of POPs and two families of herbicides were measured within a region of Northern France as part of the French National Soil Monitoring Network (RMQS: Réseau de Mesures de la Qualité des Sols). We also gather information on five covariates (elevation, soil organic carbon content, road density, land cover and population density) which might influence POP concentrations. The study region contains 105 RMQS observation sites arranged on a regular square grid with spacing of 16 km. The observations include hot-spots at sites of POP application, smaller concentrations where POPs have been dispersed and observations less than the limit of quantification (LOQ) where the soil has not been impacted by POPs. Fifty nine of the molecules were detected at less than 50 sites and hence the data were unsuitable for spatial analyses. We represent the variation of the remaining 31 molecules by various linear mixed models which can include fixed effects (i.e. linear relationships between the molecule concentrations and covariates) and spatially correlated random effects. The best model for each molecule is selected by the Akaike Information Criterion. For nine of the molecules, spatial correlation is evident and hence they can potentially be mapped. For four of these molecules, the spatial correlation cannot be wholly explained by fixed effects. It appears that these molecules have been transported away from their application sites and are now dispersed across the study region with the largest concentrations found in a heavily populated depression. More complicated statistical models and sampling designs are required to explain the distribution of the less dispersed molecules.     

Feature integration and spatial attention: More evidence of a dissociation between endogenous and exogenous orienting.

Prior research using a visual orienting paradigm has shown that spatial attention appears to play a greater role in detecting a conjunction of features than in detecting simple features (W. Prinzmetal et al, 1986; A. Treisman, 1985). However 1 study using this procedure (K. Briand and R. M. Klein; see record 1987-23943-001) reported that this pattern is obtained only when spatial attention is oriented exogenously (reflexively), not when it is oriented endogenously (voluntarily). Five experiments attempted to replicate and extend this finding of Briand and Klein while including procedures that addressed some of the criticisms directed at these aforementioned studies by Y. Tsal (1989a, 1989b). The data indicate that the findings reported by Briand and Klein were reliable and robust; spatial orienting effects were greater when the task required detection of conjunctions as opposed to features, but only when attention was directed by exogenous cues. A reason for this dissociation is proposed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Three-dimensional SOI-MEMS constructed by buckled bridges and vertical comb drive actuator

A new method for realizing three-dimensional structures based on the standard silicon-on-insulator microelectromechanical systems is developed using vertically buckled bridges as structural elements. The vertical displacement, profile of the bridge, and obtainable accuracy of the displacement are examined. Using the lateral dimension control of the bridge and the supporting beams, the vertical positioning is realized based on the planer photolithography. As a demonstration, a vertical comb drive actuator is prepared and its performance is examined.     

Pseudopeptide TASP inhibitors of HIV entry bind specifically to a 95-kDa cell surface protein

The template assembled synthetic peptide constructs (TASP), pentavalently presenting the tripeptide KPR or RPK, are potent and specific inhibitors of human immunodeficiency virus (HIV) infection by preventing viral entry into permissive cells. Here the 5[KPsi(CH2N)PR]-TASP construct, Psi(CH2N) for reduced peptide bond, was used in studies to demonstrate its specific binding to a 95-kDa cell surface protein ligand. Compared to its nonreduced 5[KPR]-TASP counterpart, the pseudopeptide 5[KPsi(CH2N)PR]-TASP manifested higher affinity to bind to its cell surface ligand, increased activity to inhibit HIV infection, and resistance to degradation when incubated in serum from an HIV-1 seropositive individual. In ligand blotting experiments, the biotin-labeled 5[KPsi(CH2N)PR]-TASP identified a single 95-kDa protein in crude cell extracts. This 95-kDa protein (p95) is expressed on the cell surface since surface iodination of cells resulted in its labeling, and moreover, following incubation of cells with the biotin-labeled 5[KPsi(CH2N)PR]-TASP, the p95.TASP complex was recovered by affinity chromatography using avidin-agarose. All anti-HIV TASP constructs but not their control derivatives affected the binding of biotin-labeled 5[KPsi(CH2N)PR]-TASP to p95, thus emphasizing the specific nature of this binding. Since 5[KPsi(CH2N)PR]-TASP does not interact with HIV-envelope glycoproteins, our results suggest that TASP inhibitors mediate directly or indirectly a block in HIV-mediated membrane fusion process by binding to the cell surface expressed p95.     

Semantic priming and the word repetition effect in a lexical decision task.

Two experiments were conducted with 35 university students and community residents to examine the relationship between semantic priming and the word-repetition effect in lexical decisions. Although it might be expected that these phenomena are caused by the operation of similar memory processes, given current models of word recognition, the relationship between them has not been empirically investigated. In the present study, the persistance of both effects was observed, and it was found that while facilitation due to semantic priming persisted for only a short time, the word repetition effect was quite strong and long-lasting. (French abstract) (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Improving the coverage criteria of UML state machines using data flow analysis

A number of coverage criteria have been proposed for testing classes and class clusters modeled with state machines. Previous research has revealed their limitations in terms of their capability to detect faults. As these criteria can be considered to execute the control flow structure of the state machine, we are investigating how data flow information can be used to improve them in the context of UML state machines. More specifically, we investigate how such data flow analysis can be used to further refine the selection of a cost‐effective test suite among alternative, adequate test suites for a given state machine criterion. This paper presents a comprehensive methodology to perform data flow analysis of UML state machines—with a specific focus on identifying the data flow from OCL guard conditions and operation contracts—and applies it to a widely referenced coverage criterion, the round‐trip path (transition tree) criterion. It reports on two case studies whose results show that data flow information can be used to select the best transition tree, in terms of cost effectiveness, when more than one satisfies the transition tree criterion. The results also suggest that different trees are complementary in terms of the data flow that they exercise, thus, leading to the detection of intersecting but distinct subsets of faults. Copyright © 2009 John Wiley & Sons, Ltd.     

XAS study of arsenic coordination in Euglena gracilis exposed to arsenite

Among the few eukaryotes adapted to the extreme conditions prevailing in acid mine drainage, Euglenae are ubiquitous in these metal(loid)-impacted environments, where they can be exposed to As(III) concentrations up to a few hundreds of mg x L(-1). In order to evaluate their resistance to this toxic metalloid and to identify associated detoxification mechanisms, we investigated arsenic coordination in the model photosynthetic protozoan, Euglena gracilis, cultured at pH 3.2 and exposed to As(III) at concentrations ranging from 10 to 500 mg x L(-1). E. gracilis is shown to tolerate As(III) concentrations up to 200 mg * L(-1), without accumulating this metalloid. X-ray absorption spectroscopy at the As K-edge shows that, in the cells, arsenic mainly binds to sulfur ligands, likely in the form of arsenic-trisglutathione (As-(GS)3) or arsenic-phytochelatin (As-PC) complexes, and to a much lesser extent to carbon ligands, presumably in the form of methylated As(III)-compounds. The key role of the glutathione pathway in As(III) detoxification is confirmed by the lower growth rate of E. gracilis cultures exposed to arsenic, in the presence of buthionine sulfoximine, an inhibitor of glutathione synthesis. This study provides the first investigation at the molecular scale of intracellular arsenic speciation in E. gracilis and thus contributes to the understanding of arsenic detoxification mechanisms in a eukaryotic microorganism under extreme acid mine drainage conditions.