Stochastic learning in a neural network with adapting synapses

We consider a neural network with adapting synapses whose dynamics can be analitically computed. The model is made of $N$ neurons and each of them is connected to $K$ input neurons chosen at random in the network. The synapses are $n$-states variables which evolve in time according to Stochastic Learning rules; a parallel stochastic dynamics is assumed for neurons. Since the network maintains the same dynamics whether it is engaged in computation or in learning new memories, a very low probability of synaptic transitions is assumed. In the limit $N\to\infty$ with $K$ large and finite, the correlations of neurons and synapses can be neglected and the dynamics can be analitically calculated by flow equations for the macroscopic parameters of the system.Comment: 25 pages, LaTeX fil

A reciprocal legitimation: Corrado Gini and statistics in fascist Italy

This article deals with the relationship between science and politics and in particular with the reciprocal legitimation process involving research schools and political regimes. It focuses on the case of Italian statistics during the early twentieth century. Its emergence as both an independent scientific field and a national research school, in fact, went together with the rise of nationalism and the establishment of the fascist regime. The paper uses the biography of Corrado Gini to analyze the process of mutual legitimization between science and politics under fascism. Gini's academic and professional careers show in fact how actors and ideas could compete through their ability to alter the status of the discipline, the technical functions it was assigned, and to attract funds in a changing political context Gini, as an institutional entrepreneur, was able to make his research school hegemonic in Italy by leveraging the need for scientific legitimation of new state policies during World War I and under fascism. The reinterpretation he provided of his career after the end of World War II is crucial both to deconstructing this process and to shedding light on the postwar de-legitimation of Italian statistics

Multilayered polyelectrolyte microcapsules: interaction with the enzyme cytochrome C oxidase

Cell-sized polyelectrolyte capsules functionalized with a redox-driven proton pump protein were assembled for the first time. The interaction of polyelectrolyte microcapsules, fabricated by electrostatic layer-by-layer assembly, with cytochrome c oxidase molecules was investigated. We found that the cytochrome c oxidase retained its functionality, that the functionalized microcapsules interacting with cytochrome c oxidase were permeable and that the permeability characteristics of the microcapsule shell depend on the shell components. This work provides a significant input towards the fabrication of an integrated device made of biological components and based on specific biomolecular functions and properties

Image-based tracking of anticancer drug-loaded nanoengineered polyelectrolyte capsules in cellular environments using a fast Benchtop Mid-Infrared (MIR) microscope

Drug delivery monitoring and tracking in the human body are two of the biggest challenges in targeted therapy to be addressed by nanomedicine. The ability of imaging drugs and micro-/nanoengineered drug carriers and of visualizing their interactions at the cellular interface in a labelfree manner is crucial in providing the ability of tracking their cellular pathways and will help understand their biological impact, allowing thus to improve the therapeutic efficacy. We present a fast, label-free technique to achieve high-resolution imaging at the mid-infrared (MIR) spectrum that provides chemical information. Using our custom-made benchtop infrared microscope using a high-repetition-rate pulsed laser (80 MHz, 40 ps), we were able to acquire images with subwavelength resolution (0.8 × λ) at very high speeds. As a proof-of-concept, we embarked on the investigation of nanoengineered polyelectrolyte capsules (NPCs) containing the anticancer drug, docetaxel. These NPCs were synthesized using a layer-by-layer approach built upon a calcium carbonate (CaCO3) core, which was then removed away with ethylenediaminetetraacetic acid. The obtained MIR images show that NPCs are attached to the cell membrane, which is a good step toward an efficient drug delivery. This has been confirmed by both three-dimensional confocal fluorescence and stimulated emission depletion microscopy. Coupled with additional instrumentation and data processing advancements, this setup is capable of video-rate imaging speeds and will be significantly complementing current super-resolution microscopy techniques while providing an unperturbed view into living cells

Corrado Gini: the man and the scientist

The paper discusses the times in which Corrado Gini lived in an attempt to enrich our picture of him by adding some further information to his complex personality