Probing structural and dynamic properties of trafficking subcellular nanostructures by spatiotemporal fluctuation spectroscopy

Imaging-derived mean square displacement (iMSD) is used to address the structural and dynamic properties of subcellular nanostructures, such as vesicles involved in the endo/exocytotic trafficking of solutes and biomolecules. iMSD relies on standard time-lapse imaging, is compatible with any optical setup, and does not need to dwell on single objects to extract trajectories. From each iMSD trace, a unique triplet of average structural and dynamic parameters (i.e., size, local diffusivity, anomalous coefficient) is calculated and combined to build the "iMSD signature" of the nanostructure under study. The potency of this approach is proved here with the exemplary case of macropinosomes. These vesicles evolve in time, changing their average size, number, and dynamic properties passing from early to late stages of intracellular trafficking. As a control, insulin secretory granules (ISGs) are used as a reference for subcellular structures that live in a stationary state in which the average structural and dynamic properties of the whole population of objects are invariant in time. The iMSD analysis highlights these peculiar features quantitatively and paves the way to similar applications at the sub-cellular level, both in the physiological and pathological states

Probing Liquid-Ordered and Disordered Phases in Lipid Model Membranes: A Combined Theoretical and Spectroscopic Study of a Fluorescent Molecular Rotor

An integrated theoretical/experimental strategy has been applied to the study of environmental effects on the spectroscopic parameters of 4-(diphenylamino)phtalonitrile (DPAP), a fluorescent molecular rotor. The computational part starts from the development of an effective force field for the first excited electronic state of DPAP and proceeds through molecular dynamics simulations in solvents of different polarities toward the evaluation of Stokes shifts by quantum mechanics/molecular mechanics (QM/MM) approaches. The trends of the computed results closely parallel the available experimental results thus giving confidence to the interpretation of new experimental studies of the photophysics of DPAP in lipid bilayers. In this context, results show unambiguously that both flexible dihedral angles and global rotations are significantly retarded in a cholesterol/DPPC lipid matrix with respect to the DOPC matrix, thus confirming the sensitivity of DPAP to probe different environments and, therefore, its applicability as a probe for detecting different structures and levels of plasma membrane organization

’UNA RAPPRESENTAZIONE DI CUI NON SI CONOSCE LA TRAMA’: IL DOCUMENTARIO ITALIANO DEGLI ANNI TRENTA

Il saggio analizza la vicenda del film documentario italiano degli anni Trenta nel contesto della produzione cinematografica complessiva. in particolare si concentra sul rapporto tra cinema di propaganda e e documentario d'autore.[...

A hybrid approach to detection and tracking of unmanned aerial vehicles

This paper proposes a novel, hybrid vision-based system to autonomously detect and track a specific moving target, in our case an evader UAV (Unmanned Aerial Vehicles), with a moving camera. The framework is based on a detection stage which exploits a Faster Region-based Convolutional Neural Network (Faster R-CNN) designed to detect the Region Of Interest (ROI) associated to the UAV’s position in the image plane. The moving target is tracked by using an Optical Flow-based tracking system and a Kalman Filter is used to give temporal consistency between consecutive measurements. The tracking system is designed to be able to achieve real-time image processing on embedded systems, for this reason a lag compensation algorithm for the delay due to the Faster R-CNN computation time is implemented. Algorithm’s performance is evaluated by computing the error between the true UAV position in the image plane and the estimated position resulting from the tracking system