323,422 research outputs found

    Data-driven emergence of convolutional structure in neural networks

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    Exploiting data invariances is crucial for efficient learning in both artificial and biological neural circuits. Understanding how neural networks can discover appropriate represen-tations capable of harnessing the underlying symmetries of their inputs is thus crucial in machine learning and neuroscience. Convolutional neural networks, for example, were designed to exploit translation symmetry, and their capabilities triggered the first wave of deep learning successes. However, learning convolutions directly from translation -invariant data with a fully connected network has so far proven elusive. Here we show how initially fully connected neural networks solving a discrimination task can learn a convolutional structure directly from their inputs, resulting in localized, space-tiling receptive fields. These receptive fields match the filters of a convolutional network trained on the same task. By carefully designing data models for the visual scene, we show that the emergence of this pattern is triggered by the non-Gaussian, higher -order local structure of the inputs, which has long been recognized as the hallmark of natural images. We provide an analytical and numerical characterization of the pattern formation mechanism responsible for this phenomenon in a simple model and find an unexpected link between receptive field formation and tensor decomposition of higher -order input correlations. These results provide a perspective on the development of low-level feature detectors in various sensory modalities and pave the way for studying the impact of higher-order statistics on learning in neural networks

    La nostra salute verso l'anno 2000

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    In un viaggio attraverso il pianeta salute si delineano i cambiamenti intervenuti negli ultimi anni nella cultura sanitaria, della salute e del benessere indicando nuove problematiche e nuove possibilità d'azione

    Serve la sociobiologia? Riflessioni sul dibattito culturale e d'opinione in Italia

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    Si esaminano le opere del filone sociobiologico evidenziando diverse prospettive interne e le critiche comparse sulla stampa di opinione in Italia. Si prospetta poi una strada di confronta che permetta un confronto critico fra evoluzionismo e scienze sociali

    Creazione e distruzione del benessere sociale

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    Si esaminano i processi di generazione e degenerazione del benessere sociale in epoca contemporanea. Si originano nuovi rischi in diversi campi della vita sociale, ma è possibile anche pensare alla promozione di azioni positive per generare nuovo benessere personale, relazionale, comunitario e societario. I campi generativi del bs possono essere monitorati mediante opportuni indicatori che vanno "oltre il Pil"
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