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Single microbial cells can show important local variations of elasticity due to the complex, anisotropic composition of their walls. An example of this is the yeast during cell division, where chitin is known to accumulate in the localized region of the cell wall involved in budding. We used atomic force microscopy (AFM) to measure quantitatively the local(More)
The growth and division of Staphylococcus aureus was monitored by atomic force microscopy (AFM) and thin-section transmission electron microscopy (TEM). A good correlation of the structural events of division was found using the two microscopies, and AFM was able to provide new additional information. AFM was performed under water, ensuring that all(More)
Alzheimer's disease (AD) is a devastating disorder that leads to memory loss and dementia. Neurodegeneration of cholinergic neurons in the septum and other basal forebrain areas is evident in early stages of AD. Glutamatergic neurons are also affected early in AD. In these stages, amyloid-β-peptide (Aβ) plaques are present in the hippocampus and other(More)
Type IV pili play an important role in bacterial adhesion, motility, and biofilm formation. Here we present high-resolution atomic force microscopy (AFM) images of type IV pili from Pseudomonas aeruginosa bacteria. An individual pilus ranges in length from 0.5 to 7 microm and has a diameter from 4 to 6 nm, although often, pili bundles in which the(More)
When solving the Symmetric Positive Definite (SPD) linear system Ax = b with the conjugate gradient method, the smallest eigenvalues in the matrix A often slow down the convergence. Consequently if the smallest eigenvalues in A could be somehow " removed " , the convergence may be improved. This observation is of importance even when a preconditioner is(More)
Aeromonas salmonicida subsp. salmonicida, a bacterial pathogen of Atlantic salmon, has no visible pili, yet its genome contains genes for three type IV pilus systems. One system, Tap, is similar to the Pseudomonas aeruginosa Pil system, and a second, Flp, resembles the Actinobacillus actinomycetemcomitans Flp pilus, while the third has homology to the(More)
In this article, a new extension of affine arithmetic is introduced. This technique is based on a quadratic form named general quadratic form. We focus here on the computation of reliable bounds of a function over a hypercube by using this new tool. Some properties of first quadratic functions and then polynomial ones are reported. In order to show the(More)
Le but de ce rapport est d'´ etendre les possibilités offertes par les mé-thodes déterministes d'optimisation globale basées sur l'arithmétique d'intervalles. Ainsi de nouvelles fonctions d'inclusion basées sur des représentations affines et quadratiques ontété introduites. Leur intérêt est surtout déterminant lorsque une très grande précision est exigée(More)
Alzheimer's disease (AD) is a progressive, neurodegenerative brain disorder characterized by extracellular accumulations of amyloid β (Aβ) peptides, intracellular accumulation of abnormal proteins, and early loss of basal forebrain neurons. Recent studies have indicated that the conformation of Aβ is crucial for neuronal toxicity, with intermediate(More)