Infodemics: A new challenge for public health.

The COVID-19 information epidemic, or "infodemic," demonstrates how unlimited access to information may confuse and influence behaviors during a health emergency. However, the study of infodemics is relatively new, and little is known about their relationship with epidemics management. Here, we discuss unresolved issues and propose research directions to enhance preparedness for future health crises.

Characterization of Mesenchymal Stem Cell Differentiation within Miniaturized 3D Scaffolds through Advanced Microscopy Techniques.

Three-dimensional culture systems and suitable substrates topographies demonstrated to drive stem cell fate in vitro by mechanical conditioning. For example, the Nichoid 3D scaffold remodels stem cells and shapes nuclei, thus promoting stem cell expansion and stemness maintenance. However, the mechanisms involved in force transmission and in biochemical signaling at the basis of fate determination are not yet clear. Among the available investigation systems, confocal fluorescence microscopy using fluorescent dyes enables the observation of cell function and shape at the subcellular scale in vital and fixed conditions. Contrarily, nonlinear optical microscopy techniques, which exploit multi-photon processes, allow to study cell behavior in vital and unlabeled conditions. We apply confocal fluorescence microscopy, coherent anti-Stokes Raman scattering (CARS), and second harmonic generation (SHG) microscopy to characterize the phenotypic expression of mesenchymal stem cells (MSCs) towards adipogenic and chondrogenic differentiation inside Nichoid scaffolds, in terms of nuclear morphology and specific phenotypic products, by comparing these techniques. We demonstrate that the Nichoid maintains a rounded nuclei during expansion and differentiation, promoting MSCs adipogenic differentiation while inhibiting chondrogenesis. We show that CARS and SHG techniques are suitable for specific estimation of the lipid and collagenous content, thus overcoming the limitations of using unspecific fluorescent probes.

Vibrational phase imaging by stimulated Raman scattering via polarization-division interferometry.

Stimulated Raman scattering (SRS) allows chemical identification of substances based on their third-order nonlinear vibrational susceptibility χ(3)(ω). In its standard single-frequency implementation, SRS can only access the imaginary part of χ(3)(ω). Here we introduce interferometric SRS (iSRS), which has the capability to measure both the real and the imaginary parts of the nonlinear susceptibility. With respect to a standard SRS setup, iSRS simply requires the insertion of a few optical elements in the Stokes(pump) beam pathway to generate an intrinsically phase-coherent local oscillator. While preserving the acquisition speed and the simplicity of single-frequency SRS, iSRS considerably increases its information content by providing access to the vibrational phase, which allows one to distinguish overlapping species in congested spectra and is more robust with respect to noise.

Entropy and complexity unveil the landscape of memes evolution.

On the Internet, information circulates fast and widely, and the form of content adapts to comply with users' cognitive abilities. Memes are an emerging aspect of the internet system of signification, and their visual schemes evolve by adapting to a heterogeneous context. A fundamental question is whether they present culturally and temporally transcendent characteristics in their organizing principles. In this work, we study the evolution of 2 million visual memes published on Reddit over ten years, from 2011 to 2020, in terms of their statistical complexity and entropy. A combination of a deep neural network and a clustering algorithm is used to group memes according to the underlying templates. The grouping of memes is the cornerstone to trace the growth curve of these objects. We observe an exponential growth of the number of new created templates with a doubling time of approximately 6 months, and find that long-lasting templates are associated with strong early adoption. Notably, the creation of new memes is accompanied with an increased visual complexity of memes content, in a continuous effort to represent social trends and attitudes, that parallels a trend observed also in painting art.

Broadband stimulated Raman scattering microscopy with wavelength-scanning detection.

We introduce a high-sensitivity broadband stimulated Raman scattering (SRS) setup featuring wide spectral coverage (up to 500 cm-1) and high-frequency resolution (≈20 cm-1). The system combines a narrowband Stokes pulse, obtained by spectral filtering an Yb laser, with a broadband pump pulse generated by a home-built optical parametric oscillator. A single-channel lock-in amplifier connected to a single-pixel photodiode measures the stimulated Raman loss signal, whose spectrum is scanned rapidly using a galvanometric mirror after the sample. We use the in-line balanced detection approach to suppress laser fluctuations and achieve close to shot-noise-limited sensitivity. The setup is capable of measuring accurately the SRS spectra of several solvents and of obtaining hyperspectral data cubes consisting in the broadband SRS microscopy images of polymer beads test samples as well as of the distribution of different biological substances within plant cell walls.