Interrogating Biology with Force: Single Molecule High-Resolution Measurements with Optical Tweezers

AbstractSingle molecule force spectroscopy methods, such as optical and magnetic tweezers and atomic force microscopy, have opened up the possibility to study biological processes regulated by force, dynamics of structural conformations of proteins and nucleic acids, and load-dependent kinetics of molecular interactions. Among the various tools available today, optical tweezers have recently seen great progress in terms of spatial resolution, which now allows the measurement of atomic-scale conformational changes, and temporal resolution, which has reached the limit of the microsecond-scale relaxation times of biological molecules bound to a force probe. Here, we review different strategies and experimental configurations recently developed to apply and measure force using optical tweezers. We present the latest progress that has pushed optical tweezers’ spatial and temporal resolution down to today’s values, discussing the experimental variables and constraints that are influencing measurement resolution and how these can be optimized depending on the biological molecule under study

Attractive streetscape making pedestrians walk longer routes: the case of Kunitachi in Tokyo

There are manifold benefits of an increase in pedestrian movement, both in regard to societal and to personal wellbeing, and walkability is considered a major goal in urban design. However, it is methodologically complicated to ascertain to what extent streetscape features relating to comfort and pleasurability influence pedestrian behavior. Our hypothesis is that pedestrians, at the neighborhood scale, prefer more attractive routes even if they are longer than other possible and equally safe routes to reach a certain destination, independently of the presence of amenities. As a case study, we selected Kunitachi, an attractive city in Tokyo Prefecture, thus adding to the body of non-western empirical research on pedestrian preferences. By comparing two Space Syntax betweenness simulations of pedestrian routes – compulsory and optional – with an actual counting of pedestrian frequency on site, and with behavioral observations, we have established that simulations according to the principle of “shortest route” considerably differ from actual pedestrian frequency. Only by allowing a certain detour leeway, simulations showed a less pronounced discrepancy with reality. While further research is needed to confirm our results, this enquiry has demonstrated that, attractive streetscape features are part of the reason why local residents prefer pleasant and comfortable routes over shorter ones

Science by the sea: how nanoengineering met mechanobiology in Camogli

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