1,720,996 research outputs found
Introduction to Neural Networks: Biological Neural Network
No full textChapter 1 introduces the functional organization of the biological brain. The first section opens with the description of neurons, fundamental units of the brain. These are structures capable of collecting signals, processing them and delivering them to subsequent units. At the same time, however, they are dynamic and can change according to the conditions of their environment. A second part of the chapter is devoted to the description of synapses: the dynamics of connections between neurons is in fact the basis of the processes of learning and memorization. Both are related to the concepts of signal intensity and iteration. A detailed description of how information is stored is thus proposed. The chapter closes with a descriptive overview of some properties of the nervous environment that make it a highly interconnected tissue
Solitonic Neural Networks An Innovative Photonic Neural Network Based on Solitonic Interconnections
No full textThis book delves into optics and photonic materials, describing the development of an intelligent all-optical system capable of replicating the functional building blocks of the biological brain. Starting with an analysis of biological neuronal dynamics and traversing the state of the art of neuromorphic systems developed to date, the book arrives at a description of neural networks realized through spatial soliton technology.
After a brief introduction to the biology of neural networks (Chapter 1), the book delves into the description of the neuromorphic problem emphasizing the peculiarities of optical hardware developed to date. (Chapter 2). Chapter 3 is dedicated to the description of psychomemories , which represent the modeling of human learning according to the theories of modern neuro-psychology. This chapter provides the prerequisites for understanding how solitonic neural networks (SNNs) are able to learn and how they approach biological models. Chapter 4 focuses on the experimentation of solitonic optic neurons in thin layers of lithium niobate. Optical techniques for supervised and unsupervised learning are discussed. The entire chapter is accompanied by theoretical, simulative and experimental results. This chapter explains how an X-junction neuron is able to establish synapses, modify them, or erase them. The erasure of solitonic structures represents an important innovation in the field of nonlinear optics. Finally, Chapter 5 reports on the implementation of a network of neurons capable of processing information and storing it exactly as a human episodic memory does. The chapter ends with a number of insights into the lines of research that are currently being pursued on the basis of the results obtained.
The book is meant for graduate students and researchers in the fields of optics, photonic applications, and biology. However, the main beneficiaries of this book are senior researchers in the field of nonlinear optics and artificial intelligence. To fully understand the results, it is important to have a basic knowledge of optical physics and neuron biology
Towards Neuro-Learning Process: Pyschomemories
No full textModern neuropsychology recognizes three main types of memories: episodic, procedural and semantic. These are independent but “work” in close connection, making it possible to construct external knowledge from external stimuli, which is then consolidated and recorded.
Particular weight is given to episodic-type memory, which is the model mainly considered by the solitonic systems proposed in this manuscript
Overview of Neuromorphic Optical Systems
No full textAfter analyzing in Chap. 1 some of the most important features of the biological brain that underlie learning process and information storage, this Chapter provides a quick overview of optoelectronic and fully-optical neuromorphic techniques implemented to date. The operation and physical principles of each approach presented is described. These are grouped into three main categories called paradigms. Each neuromorphic paradigm is built on a main neural connotation. The first paradigm replicates neural excitability. The second paradigm focuses on the concept of connection between units. Finally, the third paradigm is an absolute novelty in the scientific panorama and encompasses only solitonic networks, which can replicate a tissue structure. The main difference from other neuromorphic hardware lies in their ability to self-organize according to the received stimuli, evolving accordingly over time
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
Thermo-optical Properties of MoO3 thin films in the mid-infrared and phonon frequency shift
Get PDFMoO3 is extensively studied in the mid infrared range due to the strong anisotropy of its optical properties. We investigate the mid-infrared thermo-optical properties of polycrystalline alpha-phase
Molybdenum trioxide (a-MoO3) thin films grown onto SiO2 substrates in the temperature range 20°C-250°C reporting a thermo-optic coefficient of the mean order of 10-4 K-1
Mid-infrared thermo-optical properties of α-phase MoO3 thin films grown by pulsed laser deposition
Get PDFThermo-optical properties of alpha-phase MoO3 thin films deposited by pulsed laser
deposition were carried out in the mid infrared. Temperature-dependent reflection spectra allowed to retrieve refractive index and extinction coefficient against temperature, and stable and uniquely defined MoO3 thermo-optical constants such
as dn/dT and dk/dT, which demonstrate the reliability and thermal stability of the realized films for infrared applications
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