by Keyword: Probability

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Bakker, G. J., Eich, C., Torreno-Pina, J. A., Diez-Ahedo, R., Perez-Samper, G., Van Zanten, T. S., Figdor, C. G., Cambi, A., Garcia-Parajo, M. F., (2012). Lateral mobility of individual integrin nanoclusters orchestrates the onset for leukocyte adhesion Proceedings of the National Academy of Sciences of the United States of America 109, (13), 4869-4874

Integrins are cell membrane adhesion receptors involved in morphogenesis, immunity, tissue healing, and metastasis. A central, yet unresolved question regarding the function of integrins is how these receptors regulate both their conformation and dynamic nanoscale organization on the membrane to generate adhesion-competent microclusters upon ligand binding. Here we exploit the high spatial (nanometer) accuracy and temporal resolution of single-dye tracking to dissect the relationship between conformational state, lateral mobility, and microclustering of the integrin receptor lymphocyte function-associated antigen 1 (LFA-1) expressed on immune cells. We recently showed that in quiescent monocytes, LFA-1 preorganizes in nanoclusters proximal to nanoscale raft components. We now show that these nanoclusters are primarily mobile on the cell surface with a small (ca. 5%) subset of conformational- active LFA-1 nanoclusters preanchored to the cytoskeleton. Lateral mobility resulted crucial for the formation of microclusters upon ligand binding and for stable adhesion under shear flow. Activation of high-affinity LFA-1 by extracellular Ca 2+ resulted in an eightfold increase on the percentage of immobile nanoclusters and cytoskeleton anchorage. Although having the ability to bind to their ligands, these active nanoclusters failed to support firm adhesion in static and low shear-flow conditions because mobility and clustering capacity were highly compromised. Altogether, our work demonstrates an intricate coupling between conformation and lateral diffusion of LFA-1 and further underscores the crucial role of mobility for the onset of LFA-1 mediated leukocyte adhesion.

Keywords: Cumulative probability distribution, Integrin lymphocyte function-associated antigen 1, Intercellular adhesion molecule, Single molecule detection

Pomareda, Victor, Marco, Santiago, (2011). Chemical plume source localization with multiple mobile sensors using bayesian inference under background signals Olfaction and Electronic Nose: Proceedings of the 14th International Symposium on Olfaction and Electronic Nose AIP Conference Proceedings (ed. Perena Gouma, SUNY Stony Brook), AIP (New York City, USA) 1362, (1), 149-150

This work presents the estimation of a likelihood map for the location of a source of chemical plume using multiple mobile sensors and Bayesian Inference. Previously described methods use a single sensor and just binary detections (concentrations above or below a certain threshold). The main contribution of this work is to extend previous proposals to use concentration information while at the same time being robust against the presence of background signals. The algorithm has two parts. The first part, concerning Adaptive Background Estimation, uses robust statistics measurements to estimate the background level despite the intermittent presence of high concentrations due to plume statistics. The second part of the algorithm estimates likelihood functions for background and for condition plus plume. Then, the algorithm sequentially builds a likelihood probability map for the location of the source. The algorithm allows the use of multiple mobile sensors. The simulation results demonstrate that our algorithm estimates better the source location and is much more robust in the presence of false alarms.

Keywords: Sensors, Inference mechanisms, Probability, Simulation