28 research outputs found
Automated Force Volume Image Processing for Biological Samples
Atomic force microscopy (AFM) has now become a powerful technique for investigating on a molecular level, surface forces, nanomechanical properties of deformable particles, biomolecular interactions, kinetics, and dynamic processes. This paper specifically focuses on the analysis of AFM force curves collected on biological systems, in particular, bacteria. The goal is to provide fully automated tools to achieve theoretical interpretation of force curves on the basis of adequate, available physical models. In this respect, we propose two algorithms, one for the processing of approach force curves and another for the quantitative analysis of retraction force curves. In the former, electrostatic interactions prior to contact between AFM probe and bacterium are accounted for and mechanical interactions operating after contact are described in terms of Hertz-Hooke formalism. Retraction force curves are analyzed on the basis of the Freely Jointed Chain model. For both algorithms, the quantitative reconstruction of force curves is based on the robust detection of critical points (jumps, changes of slope or changes of curvature) which mark the transitions between the various relevant interactions taking place between the AFM tip and the studied sample during approach and retraction. Once the key regions of separation distance and indentation are detected, the physical parameters describing the relevant interactions operating in these regions are extracted making use of regression procedure for fitting experiments to theory. The flexibility, accuracy and strength of the algorithms are illustrated with the processing of two force-volume images, which collect a large set of approach and retraction curves measured on a single biological surface. For each force-volume image, several maps are generated, representing the spatial distribution of the searched physical parameters as estimated for each pixel of the force-volume image
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Oral history interview with Norman Powell 1971; Audio Clip
Journalist and advertising manager Norman Powell discusses qualities other than the ability to make a profit that make a good newspaper man.
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Excerpt from full interview with Norman Powell: https://dx.doi.org/10.7916/d8-y8yw-jb16
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Reproduced in Meddlesome Practices: Oral Histories of Good Troublemaking in Business is an online exhibition of business-related oral histories from the Oral History Archive at Columbia. Visit the exhibition website here: https://blogs.cul.columbia.edu/rbml/2022/03/01/meddlesome-practices
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Oral history interview with Doris Wooten Wesley 1971; Audio Clip 1
Doris Wooten Wesley, a social worker and newspaper publisher, describes the crucial role of advertising from Black businessmen and Black churches, who purchased advertisements in her family’s newspaper.
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Excerpt from full interview with Doris Wooten Wesley: https://dx.doi.org/10.7916/d8-82tm-xn83
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Reproduced in Meddlesome Practices: Oral Histories of Good Troublemaking in Business is an online exhibition of business-related oral histories from the Oral History Archive at Columbia. Visit the exhibition website here: https://blogs.cul.columbia.edu/rbml/2022/03/01/meddlesome-practices
Recommended from our members
Oral history interview with Doris Wooten Wesley 1971; Audio Clip 2
Doris Wooten Wesley describes her late husband Carter Wesley’s dedication to reporting on racist policing in their newspaper even when police reacted with violence, which eventually led to Carter Wesley’s death.
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Excerpt from full interview with Doris Wooten Wesley: https://dx.doi.org/10.7916/d8-82tm-xn83
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Reproduced in Meddlesome Practices: Oral Histories of Good Troublemaking in Business is an online exhibition of business-related oral histories from the Oral History Archive at Columbia. Visit the exhibition website here: https://blogs.cul.columbia.edu/rbml/2022/03/01/meddlesome-practices
Complexe immobilier intersyndical CGT. Montreuil, Seine Saint-Denis. Doublet geothermique pour climatisation. Reseau de surveillance hydrodynamique et hydrothermique, Octobre 1983-Novembre 1984
SIGLECNRS RP400(213) / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc
Complexe immobilier intersyndical CGT, 93100 Montreuil. Stockage intersaisonnier. Etude geochimique
CNRS RP400(236) / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc