1,721,029 research outputs found
Recensione a Conti, Daniele. 2023. I ‘quadernucci’ di Niccolò Machiavelli. Frammenti storici Palatini. Introduzione, edizione critica e commento
No full textRecensione a Conti, Daniele. 2023. I ‘quadernucci’ di Niccolò Machiavelli. Frammenti storici Palatini. Introduzione, edizione critica e comment
Neuromorphic systems based on memristive devices - From the material science perspective to bio-inspired learning hardware
Get PDFHardware computation is facing in the present age a deep transformation of its own paradigms. Silicon based computation is reaching its limit due to the physical constraints of transistor technology. As predicted by the Moore’s law, downscaling
of transistor dimensions doubled each year since the 60s, leading nowadays to the extreme of 16-nm channel width of the present state-of-the-art technology. No further improvement is possible, since laws of physics impose a different electrical
behavior when lower dimensions are attempted. Multiple solutions are then envisaged, spanning the range from quantum computing to neuromorphic computing.
The present dissertation wants to be a preliminary study for understanding the opportunities enabled by neuromorphic computing based on resistive switching memories. In particular, brain inspires technology and architecture of new generation processors because of its unique properties: parallel and distributed computation, superposition of processing and memory unit, low power consumption, to cite only some of them. Such features make brain particularly efficient and robust against degraded data, further than particularly suitable to process and store in memory new nformation. Despite many research projects and some commercial products are already proposing brain-like computing processors, like spiNNaker or IBM’s Bluenorth, they only mimic the brain functioning with standard Silicon technology, that is inherently serial
and distinguish between processing and memory unit. Resistive switching technology on the other hand, would allow to overcome many of these issues, enabling a far better match between biological and artificial neuromorphic computation.
Resistive switching are, generally speaking, Metal-Insulator-Metal structures able to change their electrical conductance as a consequence of the history of applied electric signal. In such sense, they behave exactly as synapses do in a biological
neural networks. For this reason, resistive switching when modeled as memristor, i.e. memory-resistor, can act as artificial synapses and, moreover, are particularly suitable to be interfaced with artificial Silicon neurons that are designed to replicate the biological behavior when excited with electric pulses. Anyhow, from the technological standpoint, there is still no standard on the design and fabrication of resistive switching, so that multiple structure and materials are investigated.
In this dissertation, it is reported an analysis of multiple resistive switching devices, based on various materials, i.e. TiO2, ZnO and HfO, and device architectures, i.e. thin film and nanostructured devices, with the scope of both characterizing and
comprehending the physics behind resistive switching phenomena. Furthermore, numerical simulations of artificial spiking neural networks, embedding Silicon neurons and HfO-based resistive switching are designed and performed, in order to give a systematic analysis of the performances reached by this new kind of computing paradigm
Tractatus catholice veritatis contra errores Zanzini de Soltia di Jaume Gil (1459): introduzione ed edizione
Get PDFNel 1459 Pio II emanò una bolla (Cum sicut accepimus, pubblicata a stampa solo
nel Seicento) in cui si condannavano le idee radicali di un canonico bergamasco, Za-
nino da Solza. A partire da questo testo la tradizione del libertinismo erudito rico-
nobbe in Zanino un precursore della tesi dell’impostura delle religioni. Fino ad ora la
bolla di Pio II è stata l’unica fonte su cui gli studiosi hanno cercato di ricostruire il
pensiero di Zanino, che oltre al carattere transitorio del cristianesimo avrebbe soste-
nuto un’altra serie di proposizioni eretiche, come il preadamitismo, la consunzione
naturale del mondo per conflagrazione individuabile attraverso calcoli astrologici, e
la liceità della lussuria al di fuori del matrimonio. Il contributo presenta lo studio e
l’edizione critica di un secondo documento, inedito, di eccezionale valore per rico-
struire storicamente la figura di Zanino: il Tractatus catholice veritatis contra erro-
res Zanzini de Soltia, composto nel 1459 dal Maestro del Sacro Palazzo Jaume Gil
su richiesta di Pio II. Nella prima parte il saggio ricostruisce le ragioni storiche, poli-
tiche e religiose che stanno all’origine del Tractatus, analizzando criticamente il va-
lore della fonte e facendo luce sia sul pensiero di Zanino che su quello del suo de-
trattore. Segue l’edizione critica del testo. Il Tractatus è trasmesso da due testimoni
indipendenti: il cod. 874 della Biblioteca Casanatense e il cod. F IX 2 della Univer-
sitätsbibliothek di Basilea, che contiene numerosi altri testi umanistici e appartenne
alla biblioteca dello stampatore protestante Iohannes Oporinus. Di particolare interes-
se storico-culturale risulta il manoscritto miscellaneo di Basilea, che qui si ipotizza
sia stato assemblato nella cerchia del cardinale Iacopo Ammannati Piccolomini.In 1459 Pius II issued a bull (Cum sicut accepimus, which was published only in the
seventeenth century) to condemn the radical ideas of a canon from Bergamo, Zanino da
Solza. It was by reading this text that libertins érudits made Zanino a forerunner of the thesis
of the religious imposture of Christianity, Hebraism and Islam. Until now the bull issued by
Pius II was the only source on which scholars have based the reconstruction of Zanino’s religious
thought, who in addition to the transitory nature of Christianity would have supported other
heretical propositions, such as preadamitism, the consumption of the natural world by a
conflagration predictable through astrology, and the lawfulness of lust outside marriage. The
article presents the study and a critical edition of a second, unpublished document, which is
of exceptional value in reconstructing the historical figure of Zanino: the Tractatus catholice
veritatis contra errores Zanzini de Soltia, composed in 1459 by the Master of the Sacred
Palace Jaume Gil upon request of Pius II. In the first part the essay retraces the historical,
political and religious reasons that were at the origin of the Tractatus, by analyzing the value
of the source and shedding light on both the thought of Zanino and that of his detractor. The
second section presents the critical edition of the text. The Tractatus is transmitted by two
independent witnesses: the cod. 874 of the Casanatense Library and the cod. F IX 2 of the
Universitätsbibliothek Basel, which had belonged to the library of Iohannes Oporinus and
contains other humanistic texts. The composite manuscript held at the Basel University
Library has also a particular historical and cultural value, since, as the article hypotizes, it
probably has been assembled in the circle of Cardinal Iacopo Ammannati Piccolomini
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Propagating speed waves in flocks: A mathematical model
Get PDFAn efficient collective response to external perturbations is one of the most striking abilities of a biological system. One of the crucial aspect of this phenomenon is given by the information transfer, and resulting propagation of signals, within the group. In this respect the existence of density waves that propagate linearly on a flock of birds is well known. However, most aspects of this phenomenon are still not fully captured by theoretical models. In this work we present a model for the propagation of speed fluctuations inside a flock, which is able to reproduce the observed density waves. We study the full solution of the model in d=1, and we find a line in the parameter space along which the system relaxes as fast as possible without oscillating, resembling a generalized critical damping condition. By analyzing the parameters plane we show that this "critical damping" line indeed represents an attractor for a steepest descent dynamics of the return time of the system. Finally we propose a method to test the validity of the model through future experiments.Fil: Cavagnaro, Romina Andrea. Consiglio Nazionale delle Ricerche; ItaliaFil: Conti, Daniele. Università degli studi di Roma "La Sapienza; ItaliaFil: Giardina, Irene. Università degli studi di Roma "La Sapienza; ; ItaliaFil: Grigera, Tomas Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física de Líquidos y Sistemas Biológicos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física de Líquidos y Sistemas Biológicos; Argentin
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