779 research outputs found
Active fixation as an efficient coding strategy for neuromorphic vision
No full textAbstract Contrary to a photographer, who puts a great effort in keeping the lens still, eyes insistently move even during fixation. This benefits signal decorrelation, which underlies an efficient encoding of visual information. Yet, camera motion is not sufficient alone; it must be coupled with a sensor specifically selective to temporal changes. Indeed, motion induced on standard imagers only results in burring effects. Neuromorphic sensors represent a valuable solution. Here we characterize the response of an event-based camera equipped with fixational eye movements (FEMs) on both synthetic and natural images. Our analyses prove that the system starts an early stage of redundancy suppression, as a precursor of subsequent whitening processes on the amplitude spectrum. This does not come at the price of corrupting structural information contained in local spatial phase across oriented axes. Isotropy of FEMs ensures proper representations of image features without introducing biases towards specific contrast orientations
A Bio-Inspired Neuromorphic Active Vision System Based on Fixational Eye Movements
No full textSimilar to biological retinas, neuromorphic Dynamic Vision Sensor (DVS) devices only respond to changes in the visual scene. It has been observed that in biological systems there is a causal relationship between fixational eye movements and target visibility during fixation, which plays a central role in vision. Based on these findings we implemented an active vision system comprising of a DVS mounted on a pan-tilt unit to introduce microscopic and erratic camera movements as a pivot for artificial vision of static scenes. The key principle is that moving the sensor over an image shifts the low temporal frequency power of a static scene into a range that an event-based retina can properly signal and encode it as highly synchronous activity. By characterizing the signal provided by the active vision system we evidenced (1) an amplification of its response to high spatial frequencies; (2) a whitening effect when scaling stimulus contrast to match the structure of natural images; and (3) an equalized response to all possible orientations of static stimuli related to the isotropic statistics of the random-like motion. The design of a further proper anisotropic spatial summation of events with opponent contrast polarity in a biologically-realistic spiking neural network allowed the detection of information relative to the local orientation of stimuli in a fully bio-inspired fashion. We validate the system proposed with experimental results using synthetic control stimuli
“Heat transfer on array of water drops naturally oscillating on hot surface above the Leidenfrost temperature”
No full textDevelopment and validation of a learning progression for change of seasons, solar and lunar eclipses, and moon phases.
No full textIn this paper, we report about the development and validation of a learning progression about the Celestial Motion big idea. Existing curricula, research studies on alternative conceptions about these phenomena, and students’ answers to an open questionnaire were the starting point to develop initial learning progressions about change of seasons, solar and lunar eclipses, and Moon phases; then, a two-tier multiple choice questionnaire was designed to validate and improve them. The questionnaire was submitted to about 300 secondary students of different school levels (14 to 18 years old). Item response analysis and curve integral method were used to revise the hypothesized learning progressions. Findings support that spatial reasoning is a key cognitive factor for building an explanatory framework for the Celestial Motion big idea, but also suggest that causal reasoning based on physics mechanisms underlying the phenomena, as light flux laws or energy transfers, may significantly impact a students’ understanding. As an implication of the study, we propose that the teaching of the three discussed astronomy phenomena should follow a single teaching-learning path along the following sequence: (i) emphasize from the beginning the geometrical aspects of the Sun-Moon-Earth system motion; (ii) clarify consequences of the motion of the Sun-Moon-Earth system, as the changing solar radiation flow on the surface of Earth during the revolution around the Sun; (iii) help students moving between different reference systems (Earth and space observer’s perspective) to understand how Earth’s rotation and revolution can change the appearance of the Sun and Moon. Instructional and methodological implications are also briefly discussed
Studiare organizzazione aziendale come ambito di produzione culturale
No full textNei corsi di studio a carattere economico aziendale, dove è sovente riscontrabile una sorta di ansia da troppa teoria, la faccenda è ancora più evidente. Le motivazioni di questo modo di intendere il ruolo dello studio durante gli anni della propria formazione sono rintracciabili da un lato in una consolidata tradizione che considera (a torto o a ragione) applicative le discipline manageriali, dall’altro trovano riscontro nelle recenti tendenze del Legislatore, che ha riformato negli ultimi anni le Politiche della formazione primaria, secondaria e universitaria, ispirandosi a logiche di education di matrice anglosassone, un po’ per l’esigenza di armonizzare le pratiche sociali tra i Paesi europei, un po’ in ragione della cornice neoliberista entro cui siamo portati a muoverci, spesso acriticamente, in molti campi del nostro agire e interagire. Si pensi, ad esempio, al tirocinio formativo (prima “Alternanza Scuola-Lavoro, oggi PCTO) presente lungo gran parte dei processi di scolarizzazione delle nuove generazioni, che si basa proprio sull’idea di accorciare quella distanza tra teoria e pratica. Inoltre, pensino gli studenti anche alle possibili offerte di carriera con cui entrano in contatto dopo il completamento del percorso di laurea, come, ad esempio, i tirocini aziendali e le diverse forme di apprendistato che alimentano l’idea (e il timore) di una difficoltà a far sintesi tra ciò che si è studiato e ciò che si è in grado di fare in azienda. In questo Capitolo non entreremo nel merito di questo interessante dibattito, assai articolato in tante sfaccettature, ma – indipendentemente dalle idee che si possono avere su questo argomento – si vuole innanzitutto rilevare come sia diffusa, tanto nei libri di testo quanto nei corsi d’Organizzazione Aziendale (e non solo), la consuetudine di affrontare il tema delle distanze tra teoria e pratica, attraverso diverse modalità: per citarne alcune, il continuo richiamo ad esempi e a “casi di scuola” tratti dalle realtà delle organizzazioni aziendali, oppure facendo ricorso alla presenza di testimoni (manager, professionisti, ecc...) che portano in aula i propri contributi d’esperienza agli studenti o, ancora e non da ultimo, l’adozione a fianco di un manuale, di uno o più testi spesso volutamente focalizzati su strumenti di management riferiti a specifiche realtà aziendali. Tutto ciò ha lo scopo di suscitare negli studenti una propria abilità a ragionare autonomamente e a costruire un pensiero critico e flessibile sul mondo delle organizzazioni aziendali, fino a sviluppare delle competenze in termini di diagnosi organizzativa (Sicca, 2020)
Dal diapason al Sole: una proposta innovativa per l'insegnamento delle onde meccaniche
No full textIn questo lavoro presentiamo un modulo innovativo che ha lo scopo di affrontare le piu comuni misconcezioni degli studenti riguardo le onde meccaniche, attraverso la fusione di un contesto tradizionale quale lo studio del suono di un diapason con uno insolito quale lo studio del suono prodotto dal Sole. Gli studenti, utilizzando un software audio digitale, determinano la frequenza fondamentale di un diapason e quindi la frequenza fondamentale delle oscillazioni del Sole. Inoltre viene mostrato come in Fisica si possa utilizzare la stessa tecnica (analisi spettrale) per ottenere informazioni riguardo fenomeni fisici molto diversi. Il modulo e stato proposto in via sperimentale nell'anno scolastico 2014-2015 durante il Piano Lauree Scientiche - Fisica presso l'Universitàa di Napoli a circa 40 studenti frequentanti la classe quarta di Liceo Scientico. Questa sperimentazione sarà il punto di partenza per la realizzazione di uno strumento di valutazione finalizzato ad indagare l'efficacia delle attivitàa presenti nel modulo
Organizzazione e musica, ovvero organizzare e suono
No full textObiettivo di questo Capitolo è di argomentare il binomio organizzazione e musica, attraverso l’impianto di fondo di questo volume, che legge l’azione organizzativa in termini di attori, declinati in quattro livelli: individuo, gruppo, azienda e network. A tale scopo, si adotterà parzialmente o quasi per nulla l’opzione metaforica, considerando la musica, nelle sue plurali declinazioni, una millenaria forma reale di organizzazione o, più correttamente, dell’organizzare (Czarniawska, [2014] 2020) che molto ha da dire e da dare a quelle più recenti (appena centenarie) forme di organizzazione che si riconoscono nell’impresa industriale e di servizi, siano esse private o pubbliche amministrazioni (Sicca, 2000; 2008). Così facendo, si proporrà ai lettori di questo volume uno spazio di pensiero e di azione materiale, anche nella quotidianità delle pratiche sociali e manageriali, che possa fare rifermento a un
costrutto: “Per una economia della musica” (Sicca, Napolitano, 2021). L’invito, dunque, è
quello di abbandonare la metafora, favorendo un approccio che non inquadra la musica co-
me organizzazione, ma che ci invita a comprendere che la musica è organizzazione (e viceversa, forse)
Intersubjetividade, natureza e sentimentos morais. A teoria crítica de A. Honneth e a regra de ouro
No full textThe text raises the question of the conditions for the possibility of intersubjectivity in the theory of recognition. An analysis of the theory of recognition formulated by Axel Honneth shows how the conflict determined by moral motivations relativizes the Habermasian premise of the linguistic understanding and brings the normative dimension back to social theory. The author returns to the pages of the Encyclopedia of Hegel to recover the objective dimension of intersubjectivity and highlights problems in Honneth’s theoretical project. He confronts both the linguistic-hermeneutic and the recognition paradigm with his pressuposition of this intersubjectivity that yet have to be established, and concludes that the theory of recognition can not explain the normative basis of intersubjectiv recognition. This theory, so Testa, describes contexts of interaction and not moral imperatives. The golden rule, especially his negative formulation is seen as a better codification of the requirement to give recognition without neglecting the experience of offenses and fight; it is seen as a better positive justification of the norms of reciprocity.O texto coloca a questão das condições de possibilidade da intersubjetividade na teoria do reconhecimento. Uma análise da teoria do reconhecimento formulada por Axel Honneth mostra como o conflito determinado por motivações morais relativiza o postulado Habermasiano do entendimento lingüístico e traz de volta a dimensão normativa à teoria social. O autor faz um retorno às páginas da Enciclopédia de Hegel para recuperar a dimensão objetiva da intersubjetividade e destacar problemas teóricos no projeto de Honneth. Com isso passa a confrontar tanto o paradigma lingüísticohermenêutico como o do reconhecimento com o fato de pressuporem a intersubjetividade a ser ainda constituída, para concluir que a teoria do reconhecimento não consegue explicitar um núcleo normativo do reconhecimento intersubjetivo; ela descreve contextos de interação e não imperativos morais. A da regra de ouro, em especial na formulação negativa (“não faças a ninguém aquilo que não gostarias que fosse feito a ti – Tb 4,15) é vista como melhor codificação da exigência de reconhecimento sem prescindir da experiência da ofensa e da luta, como melhor justificação positiva das normas de reciprocidade. Palavras-chave: Regra de ouro; Reciprocidade; Reconhecimento; Axel Honnet
Gradazione di tratti distintivi della letteratura dell’esodo nel romanzo La zaratina di Silvio Testa
No full textThe Italian literature of exile, pervaded by a bitter feeling of memories, has been enriched by another literary memory - Silvio Testa’s novel La zaratina, tragedy of Dalmatian exile. This consonant literature about the distinctive elements of Italianity - Romanity of Dalmatia - finds in Testa’s book a significant reinforcement of those elements and symbols, presented in almost all works of fiction and non-fiction dealing with the tragedy of the exile of Italians and other populations from the eastern coast of the Adriatic. The aim of this analysis is to detect and present the new contribution Silvio Testa offers to the memorial landscape of this traumatic historical experience - particularly through his depiction of the massacre and destruction of Zadar (Zara), caused by Anglo-American bombardments during World War II. Through the intimate and multi-generational portrait of the Italian family of the protagonist Bepi (Giuseppe), Testa elevates Zadar - nicknamed “the Adriatic Dresden” - into a literary monument: a testament to human survival, a symbol of the enduring vitality of its people, and of the solidarity that once existed between Italians and Croats, all immersed in the brutality of war. Testa’s novel is an exceptional contribution to the realist-naturalistic strand of Italian exile literature. The narrative moves beyond political or ideological accounts to construct a cubist mosaic of memory, trauma, and identity. At its core lies the deep pain of the disintegration of a multiethnic coexistence in Zadar - a city where Italians and Slavs once shared churches, schools, and family ties. Testa identifies nationalism, religion, and ideology as the three poisonous forces that shattered this balance. These motifs are not simply abstract ideas but are manifested through a wide range of emotionally charged and historically grounded episodes in the novel. The characters of Luigi, Daria, and Ivo offer insight into how personal identities and relationships were destroyed by political and ethnic divisions. Ivo, in particular, embodies the complex fluidity of Dalmatian identity: born an Austrian subject, raised with Italian culture, and of Croatian descent, his very being is rendered suspicious in a world divided into rigid national categories. When stopped by Yugoslav partisans and accused of fraternizing with Italians, Ivo understands that his deeply rooted ties to Zadar’s Italian community are no longer understandable to outsiders. His inner turmoil becomes emblematic of the cultural loss experienced by many Dalmatians. The novel also pays close attention to emotional and symbolic landscapes. Even in rare moments of physical pleasure, such as an erotic scene between Luigi and Daria, the mood is eclipsed by a looming sense of separation and despair. This episode illustrates Testa’s ability to merge intimacy and tragedy, making the body itself a battlefield of exile. An essential narrative device in the novel is the meticulous naming of real people and historically verifiable events. The autor of the article, himself born in Zadar during the bombings, confirms personal knowledge of many figures in the novel - such as Ivo and Sergio Nežić, or the partisan Obrad Egić - thereby blurring the boundary between literature and testimony. These elements add documentary weight to the story and deepen the realism that defines the novel’s contribution to the memorialization of the exodus. One of the most memorable figures in the novel is Ivaniza, a young maid from the island of Ugljan. Far from being a secondary character, she emerges as a moral compass and savior figure - risking her life to help Luigi and others. Ivaniza becomes a secular symbol of providence, akin to characters from Manzoni’s The Betrothed, silently ensuring the family’s survival amidst collapse. Her inclusion as a central character also reflects Testa’s egalitarian vision of heroism and dignity during wartime. In one of the darkest scenes of the novel, Daria is shown a bag containing human eyeballs by a group of partisans - a horrifying moment that unmistakably recalls Curzio Malaparte’s Kaputt, particularly the scene where Ante Pavelić is presented with a basket of Serbian eyes by his Ustaše followers. This intertextual echo links Testa’s work to a broader tradition of European literature that denounces wartime atrocities, while grounding the horror in the specific context of Zadar. The ultimate emotional and symbolic weight of the novel rests with Daria and her relationship to music, particularly the piano. In pre-exile Zadar, her piano was a source of self-expression and identity. After the family’s displacement, Daria clings to this artistic anchor - at one point drawing a keyboard on wood just to “play.” But by the end, the piano becomes a metaphor of emotional death. In a climactic scene in Venice, Daria breaks down at the instrument, crying silently as her fingers produce a dissonant, painful sound. She closes the lid as if closing the chapter of her life connected to Zadar. Her final gesture of turning her back on the piano reflects a complete internal collapse, the psychological endpoint of exile. Through Daria’s grief, Testa communicates a collective pain. She becomes a pars pro toto, representing all exiles - people from Zadar, Dalmatia, and beyond - whose spiritual devastation parallels the destruction of their cities. The novel’s closing pages form a threnody for Zadar, a dirge for a world that no longer exists, leaving only scars and muted songs. In conclusion, La zaratina stands as a masterful literary and historical contribution to the memory of the Italian exodus. With emotional precision, historical veracity, and a powerful sense of place and identity, Silvio Testa offers a unique reinforcement of the symbolic, cultural, and human elements that have shaped the literature of Dalmatian and Julian exile. His novel joins the canon of this literature not as an imitation, but as a deeply personal, stylistically rich, and morally profound work - one that reminds us how loss of homeland is not just a historical fact but a wound that sings, cries, and remembers.Lo studio prende in esame il romanzo La zaratina (2017) del giornalista veneziano Silvio Testa, esule di seconda generazione. Nell’intervento si cercherà di identificare e presentare il nuovo contributo dell’autore all’immagine memorialistica della strage, disgrazia zaratina a causa dei bombardamenti angloamericani. La “Dresda adriatica”, tramite la famiglia italiana del protagonista Giuseppe, diventa un monumento alla sopravvivenza umana, nonché un simbolo della vitalità dei protagonisti e della solidarietà degli italiani e dei croati immersi nella brutalità bellica. Il presente romanzo della convincente documentazione storica, scritto con naturalismo nostalgico, è una testimonianza storica di alto livello letterario realistico-finzionale
Fixation Drifts in Neuromorphic Vision Sensing & Computing: a Natural Approach for Effective Space-Time Encoding of Static Scenes
No full textDespite the name, human fixation is a highly dynamic process. Contrary to a photographer, who puts a great effort in keeping the lens still, eyes incessantly move even during fixation, to the point visibility would otherwise rapidly fade away. Beyond avoiding perceptual fading, many functional advantages of Fixational Eye Movements have been pointed out in biology, persuading the scientific community that FEMs are far from being a nuisance as originally believed. On the wave of these findings, I investigate their role in neuromorphic vision sensing and processing, hence bridging two active research fields: vision neuroscience and neuromorphic computing. By emulating primary functionalities of the human retina, neuromorphic cameras represent a convenient device for either investigating (by modeling) visual neuroscience theories, as well as building power-efficient robotic systems. I exploit neuromorphic technology to examine the effects of active viewing strategies during fixation, emphasizing the benefits they provide in terms of both space and time encoding of static visual inputs. My aim is to confirm main biological evidence and propose new arguments on the importance of such movements for artificial vision systems, further extendable to biological ones. The scientific questions I tackle can be expressed as follows: (1) “How do bio-inspired fixation drifts influence the spatio-temporal representation of static visual features in neuromorphic sensing?” and (2) “How does this affect subsequent processing stages?”. The first step to answer both questions is the design of a neuromorphic active- vision setup – able to finely reproduce microscopic and randomly-drifting bio-inspired motion patterns – combined with the development of a suitable software toolkit. This enables to effortlessly acquire significant amount of event-based data from different static visual sources, for further analysis. I then characterize the output signal of the silicon retina using either traditional computer vision algorithms, latest deep-learning architectures, and emerging spiking neural networks. Specifically, to answer the first question, I examine purely spatial information gathered from event-based recordings of natural images and synthetic stimuli. I adopt both traditional amplitude-based image correlation approaches (frequently employed for efficient coding studies in vision science), as well as more sophisticated phase-based examination techniques (coupled with Gabor filter banks for robust local feature extraction,
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and metrics inherited from neuroimaging research). The influence of motion isotropy is then evaluated based on circular statistic tests and image deconvolution techniques (refined using Tikhonov regularization). Finally, to conclude the first question, I asses the distribution events on the temporal dimension by using a custom deep-learning pipeline, together with neuromorphic data recorded from a large and well-established computer-vision dataset. The pipeline uses progressively increasing temporal scales of the data stream, and mainly comprises state-of-the-art 2D and 3D convolutional neural networks, as well as a cutting-edge spiking network model. Since the latter is particularly suitable for neuromorphic hardware implementations, this answers the second question as well. Collectively, my results prove that fixational drifts assist vision in (i) minimizing redundancy, by removing space correlations and inducing whitening effects of the amplitude spectrum, (ii) preserving relevant structural information, by retaining local phase with no alteration, (iii) acting as preliminary anisotropic filtering stages, that can be combined in time for unbiased feature extraction, (iv) inducing biologically-comparable time modulations of static visual information, by arranging events in complex spatio-temporal patterns, and (v) improving a subsequent spike-based computation, able to learn rich temporal codes for high-level vision tasks. Overall, these aspects reflect in an efficient spatio-temporal encoding of static visual scenes, that benefits both transmission and computation of spiking data downstream the hierarchical structure of the visual system. Hopefully, the modeling framework I propose could serve as a methodological basis to (i) investigate data encoding in visual systems, (ii) provide preliminary proofs or refusals of neuroscientific theories about FEMs, (ii) produce novel and suitable benchmarks for advancing the field of neuromorphic computing, and finally (iv) inspire future robotic applications to efficiently gather visual information during fixation. Since neuromorphic hardware is particularly suited for embedded and power-constrained solutions, a mechanism that helps discarding redundancy while preserving informative content can be a convenient tool for optimizing data transmission, both in terms of wiring and energy requirements. Moreover, given that spike-based algorithms and processors are particularly convenient for (and devoted to) richly time-structured data, finding an optimal strategy for effectively encoding space in time is crucial for real-world neuromorphic vision applications. Nature came up with a single elegant solution for both problems
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