222 research outputs found
Allan Variance Analysis as Useful Tool to Determine Noise in Various Single-Molecule Setups
One limitation on the performance of optical traps is the noise inherently
present in every setup. Therefore, it is the desire of most experimentalists to
minimize and possibly eliminate noise from their optical trapping experiments.
A step in this direction is to quantify the actual noise in the system and to
evaluate how much each particular component contributes to the overall noise.
For this purpose we present Allan variance analysis as a straightforward
method. In particular, it allows for judging the impact of drift which gives
rise to low-frequency noise, which is extremely difficult to pinpoint by other
methods. We show how to determine the optimal sampling time for calibration,
the optimal number of data points for a desired experiment, and we provide
measurements of how much accuracy is gained by acquiring additional data
points. Allan variances of both micrometer-sized spheres and asymmetric
nanometer-sized rods are considered.Comment: 14 pages, 6 figures, presented at SPIE Optics+Photonics 2009 in San
Diego, CA, US
Helical Buckling in Filopodia
Fitxes dels barri
Dynamic buckling of actin within filopodia
Filopodia are active tubular structuresprotruding from the cell surface which allow the cell to sense and interact with the surrounding environment through repetitive elongation-retraction cycles. The mechanical behavior of filo-podia has been studied by measuring the traction forces exerted on external sub-strates.1 These studies have revealed that internal actin flow can transduce a force across the cell surface through transmem-brane linkers like integrins. In addition to the elongation-retraction behavior filo-podia also exhibit a buckling and rota-tional behavior. Filopodial buckling in conjunction with rotation enables th
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