Search results for "mapping"
showing 10 items of 1508 documents
Application of total internal reflexion fluorescence microscopy for studying pH changes in an occluded electrochemical cell: Development of a wavegui…
2006
A device for pH mapping derived from optical sensors similar to total internal reflection fluorescence microscopy (TIRFM) has been developed for future possible applications in the field of localized corrosion. The sensing principle is the increase of the fluorescent yield of the fluorescein with the pH of the medium. The basic principle of this sensor is based on the excitation of a fluorescent silica polymer film of nanometre dimensions, deposited by sol–gel method on a waveguiding layer. The total internal reflexion conditions creates an evanescent wave which interacts with the molecules trapped in the silica layer. A conventional microscope located above the sample collects the fluoresc…
Characterization of the length polymorphism in the A + T-rich region of the Drosophila obscura group species
1993
In the twelve Drosophila obscura group species studied, belonging to the affinis, obscura, and pseudoobscura subgroups, the mitochondrial DNA length ranges from 15.8 to 17.2 kb. This length polymorphism is mainly due to insertions/deletions in the variable region of the A + T-rich region. In addition, one species (D. tristis) possess a tandem duplication of a 470-bp fragment that contains the replication origin. The same duplication has occurred at least twice in the Drosophila evolutionary history due to the fact that the repetition is analogous to repetitions found in the four species of the D. melanogaster complex. By comparing the nucleotide sequence of the conserved region in D. ambigu…
Mitochondrial DNA haplotype frequencies in natural and experimental populations of Drosophila subobscura.
1998
Abstract The evolution of Drosophila subobscura mitochondrial DNA has been studied in experimental populations, founded with flies from a natural population from Esporles (Majorca, Balearic Islands, Spain). This population, like other European ones, is characterized by the presence of two very common (>96%) mitochondrial haplotypes (called I and II) and rare and endemic haplotypes that appear at very low frequencies. There is no statistical evidence of positive Darwinian selection acting on the mitochondrial DNA variants according to Tajima's neutrality test. Two experimental populations, with one replicate each, were established with flies having a heterogeneous nuclear genetic back…
Phylogenetic reconstruction of the Drosophila obscura group, on the basis of mitochondrial DNA
1992
We have constructed restriction-site maps of the mtDNAs in 13 species and one subspecies of the Drosophila obscura group. The traditional division of this group into two subgroups (affinis and obscura) does not correspond to the phylogeny of the group, which shows two well-defined clusters (the Nearctic affinis and pseudoobscura subgroups) plus a very heterogeneous set of anciently diverged species (the Palearctic obscura subgroup). The mtDNA of Drosophila exhibits a tendency to evolve toward high A+T values. This leads to a "saturation" effect that (1) begets an apparent decrease in the rate of evolution as the time since the divergence of taxa increases and (2) reduces the value that mtDN…
Fitness and life-history traits of the two major mitochondrial DNA haplotypes of Drosophila subobscura
2004
Mitochondrial DNA restriction site analyses on natural populations of Drosophila subobscura have proved the existence of two common, coexisting haplotypes (I and II), as well as a set of less frequent ones derived from them. To explain this distribution, experiments to date point practically to all possible genetic mechanisms being involved in the changes of gene frequencies (cytonuclear coadaptation, direct natural selection on mtDNA and genetic drift). In an attempt to find differences that help to understand the dynamics of these haplotypes and to detect the effect of selection, we measured certain fitness components and life-history traits (egg-larva and larva-adult viabilities and deve…
Complete Shadowing Modeling and its Effect on System Level Performance Evaluation
2008
Computer simulations are a common procedure for assessing the performance of new algorithms. To conduct a valid and accurate study, the models employed in such simulators need to be carefully selected. Regarding shadowing modeling, one-dimensional models are fairly commonplace in the literature. While simple and with low computational costs, these models can not produce correlated fading values for mobiles that are in nearby positions and, besides, do not include the cross-correlation effect. To overcome these limitations, this paper presents a bi-dimensional shadowing model which introduces both the spatial correlation and the cross-correlation present in real systems. Finally, the impact …
Geometric quality and appearance of surfaces : local and global approaches
2012
Accounting for customers' perception of manufactured goods has become a major challenge for the industry. This process is to be established from early design to retail. Customers are nowadays more aware and detail oriented about perceived quality of products. This allows one to set not only an estimated price but also the expected quality of the product. Surface appearance analysis has therefore become a key industrial issue. Two approaches are proposed here to formalize the detection methodology and provide objective criteria for experts to evaluate surface anomalies. The first proposed approach is based on surface metrology. It consists in analyzing the measured topologies in order to bin…
Detecting global and local hippocampal shape changes in Alzheimer's disease using statistical shape models.
2012
Item does not contain fulltext The hippocampus is affected at an early stage in the development of Alzheimer's disease (AD). With the use of structural magnetic resonance (MR) imaging, we can investigate the effect of AD on the morphology of the hippocampus. The hippocampal shape variations among a population can be usually described using statistical shape models (SSMs). Conventional SSMs model the modes of variations among the population via principal component analysis (PCA). Although these modes are representative of variations within the training data, they are not necessarily discriminative on labeled data or relevant to the differences between the subpopulations. We use the shape des…
Detailed Anatomical and Electrophysiological Models of Human Atria and Torso for the Simulation of Atrial Activation
2015
Atrial arrhythmias, and specifically atrial fibrillation (AF), induce rapid and irregular activation patterns that appear on the torso surface as abnormal P-waves in electrocardiograms and body surface potential maps (BSPM). In recent years both P-waves and the BSPM have been used to identify the mechanisms underlying AF, such as localizing ectopic foci or high-frequency rotors. However, the relationship between the activation of the different areas of the atria and the characteristics of the BSPM and P-wave signals are still far from being completely understood. In this work we developed a multi-scale framework, which combines a highly-detailed 3D atrial model and a torso model to study th…
A novel bio-orthogonal cross-linker for improved protein/protein interaction analysis
2015
International audience; The variety of protein cross-linkers developed in recent years illustrates the current requirement for efficient reagents optimized for mass spectrometry (MS) analysis. To date, the most widely used strategy relies on commercial cross-linkers that bear an isotopically labeled tag and N-hydroxysuccinimid-ester (NHS-ester) moieties. Moreover, an enrichment step using liquid chromatography is usually performed after enzymatic digestion of the cross-linked proteins. Unfortunately, this approach suffers from several limitations. First, it requires large amounts of proteins. Second, NHS-ester cross-linkers are poorly efficient because of their fast hydrolysis in water. Fin…