O aprendizado de máquina consiste em conceitos e técnicas que permitem aos computadores melhorar seu desempenho com a experiência, ou em outras palavras, aprender com dados. Duas de suas principais categorias são o aprendizado não-supervisionado e o semissupervisionado, que respectivamente consistem em inferir padrões em bases cujos dados não têm rótulo (classe) e classificar dados em bases parcialmente rotuladas. Embora muito estudado, trata-se de um campo repleto de desafios e com muitos tópicos abertos. Sistemas dinâmicos coletivos, por sua vez, são sistemas constituídos por muitos indivíduos, cada qual um sistema dinâmico por si só, de modo que todos eles agem coletivamente, ou seja, a ação de cada indivíduo é influenciada pela ação dos vizinhos. Uma característica notável desses sistemas é que padrões globais podem surgir espontaneamente das interações locais entre os indivíduos, fenômeno conhecido como emergência. Os desafios intrínsecos e a relevância do tema vêm motivando sua pesquisa em diversos ramos da ciência e da engenharia. Este trabalho de doutorado consiste no desenvolvimento e análise de modelos dinâmicos coletivos para o aprendizado de máquina, especificamente suas categorias não-supervisionada e semissupervisionada. As tarefas de segmentação de imagens e de detecção de comunidades em redes, que de certo modo podem ser entendidas como tarefas do aprendizado de máquina, são também abordadas. Em especial, desenvolvem-se modelos nos quais a movimentação dos objetos é determinada pela localização e velocidade de seus vizinhos. O sistema dinâmico assim modelado é então conduzido a um estado cujo padrão formado por seus indivíduos realça padrões subjacentes do conjunto de dados. Devido ao seu caráter auto-organizável, os modelos aqui desenvolvidos são robustos e as informações geradas durante o processo (valores das variáveis do sistema) são ricas e podem, por exemplo, revelar características para realizar soft labeling e determinar classes sobrepostas. / Machine learning consists of concepts and techniques that enable computers to improve their performance with experience, i.e., learn from data. Unsupervised and semi-supervised learning are important categories of machine learning, which respectively consists of inferring patterns in datasets whose data have no label (class) and classifying data in partially-labeled datasets. Although intensively studied, machine learning is still a field full of challenges and with many open topics. Collective dynamical systems, in turn, are systems made of a large group of individuals, each one a dynamical system by itself, such that all of them behave collectively, i.e., the action of each individual is influenced by the action of its neighbors. A remarkable feature of those systems is that global patterns may spontaneously emerge from the local interactions among individuals, a phenomenon known as emergence. Their relevance and intrinsic challenges motivate research in various branches of science and engineering. In this doctorate research, we develop and analyze collective dynamical models for their usage in machine-learning tasks, specifically unsupervised and semi-supervised ones. Image segmentation and network community detection are also addressed, as they are related to machine learning as well. In particular, we propose to work on models in which the objects motion is determined by the location and velocity of their neighbors. By doing so, the dynamical system reaches a configuration in which the patterns developed by the set of individuals highlight underlying patterns of the dataset. Due to their self-organizing nature, it is also expected that the models can be robust and the information generated during the process (values of the system variables) can be rich and reveal, for example, features to perform soft labeling and determine overlapping classes.

A self-adaptive software is developed to predict the stock market. It’s Stock Prediction Engine functions autonomously when its skill-set suffices to achieve its goal, and it includes human-in-the-loop when it recognizes conditions benefiting from more complex, expert human intervention. Key to the system is a module that decides of human participation. It works by monitoring three mental states unobtrusively and in real time with Electroencephalography (EEG). The mental states are drawn from the Opportunity-Willingness-Capability (OWC) model. This research demonstrates that the three mental states are predictive of whether the Human Computer Interaction System functions better autonomously (human with low scores on opportunity and/or willingness, capability) or with the human-in-the-loop, with willingness carrying the largest predictive power. This transdisciplinary software engineering research exemplifies the next step of self-adaptive systems in which human and computer benefit from optimized autonomous and cooperative interactions, and in which neural inputs allow for unobtrusive pre-interactions. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection

Abstract not available

L'activité neuronale est souvent considérée en neuroscience cognitive par la réponse évoquée mais l'essentiel de l'énergie consommée par le cerveau permet d'entretenir les dynamiques spontanées des réseaux corticaux. L'utilisation combinée d'algorithmes de classification (K means, arbre hirarchique, SOM) sur des enregistrements intracellulaires du cortex visuel primaire du chat nous permet de définir des classes de dynamiques neuronales et de les comparer l'activité évoquée par un stimulus visuel. Ces dynamiques peuvent être étudiées sur des systèmes simplifiés (FitzHugh-Nagumo, systèmes dynamiques hybrides, Wilson-Cowan) dont nous présentons l'analyse. Enfin, par des simulations de réseaux composés de colonnes de neurones, un modèle du cortex visuel primaire nous permet d'étudier les dynamiques spontanées et leur effet sur la réponse à un stimulus. Après une période d'apprentissage pendant laquelle des stimuli visuels sont prsentés, des vagues de dépolarisation se propagent dans le réseau. L'étude des corr ́lations dans ce réseau montre que les dynamiques spontanées reflètent les propriétés fonctionnelles acquises au cours de l'apprentissage.

Long-distance radical cation transport was studied in DNA condensates where linearized pUC19 plasmid was ligated to an oligomer and transformed into DNA condensates with spermidine. DNA condensates were detected by Dynamic Light Scattering and observed by Transmission Electron Microscopy. Introduction of charge into the condensates causes long-distance charge migration, which is detected by reaction at the remote guanines. The efficiency of charge migration in the condensate is significantly less than it is for the corresponding oligomer in solution. This result is attributed to a lower mobility for the migrating radical cation in the condensate, caused by inhibited formation of charge-transfer-effective states. Radical cation transport was also studied in DNA condensates made from an oligomer sandwiched between two linearized plasmids by double ligation. Unlike the single ligated plasmid condensates, the efficiency of charge migration in the double ligated plasmid-condensates is high, indicative of local structural and conformational transformation of the DNA duplexes. Organic monomer units having extended ð-conjugation as part of a long conducting polymer was synthesized and characterized. The monomer units were covalently attached to particular positions in DNA oligonucleotides by either the convertible nucleotide approach or by phosphoramidite chemistry. Successful attachment of the monomer units to DNA were confirmed by mass spectral analysis. The DNA-conjoined monomer units can self assemble in the presence of complementary sequences which act as templates that can control polymer formation and structure. By this method the para-direction of the polymer formation can be enforced and may be used to generate materials having nonrecurring, irregular structures.

The extent to which cortical maps may reorganize in adult humans is a significant and topical debate in visual neuroscience. Though there are conflicting findings, evidence from humans and animals indicates that the topography of the visual cortex may change after retinal deafferentation. Remarkably, this reorganization seems to be possible in adults, whose brains are less amenable to plastic change. If adult visual reorganization is legitimate, an understanding of its causes and consequences could be profound considering the millions suffering from age-related visual disorders. This dissertation explores whether visual training may yield a reorganization of sensory maps in the adult visual cortex. It describes research in which patients, diagnosed with age-related macular degeneration (AMD), underwent visual rehabilitation therapy. Functional brain scans and behavioral tests were conducted pre and post training. These interventions generated valuable knowledge regarding whether "reorganized" activity is a true rewiring of feed forward cortical processes or an artifact of attentional feedback. The rehabilitation training produced demonstrable differences in activation patterns along the primary visual cortex (V1), but sparse improvement in the behavioral tests. In contrast, there was significant improvement in fixation tests which assessed oculomotor control. These results suggest that the nature of reorganized activity has more to do with attentional mechanisms than feed forward reorganization. Future investigations could benefit from examining the brain sites that govern visual attention in the frontal and parietal cortices. These areas may have more to do with visual adaptation in AMD patients than V1.

Colloidal particles serve as useful building blocks for materials applications ranging from controlled band-gap materials to rationally designed drug delivery systems. Thus, developing approaches to direct the assembly and disassembly of sub-micron sized particles will be paramount to further advances in materials science engineering. This project focuses on using programmable and reversible binding between oligonucleotide strands to assemble and then disassemble polystyrene colloidal particles. It is shown that DNA-mediated assembly can be reversed at a fixed temperature using secondary oligonucleotide strands to competitively displace the primary strands linking particles together. It was found that 1) titrating the surface density of hybridizing probe strands and 2) adjusting the base length difference between primary and secondary target strands was key to successful isothermal disassembly. In order to titrate the surface density of primary probe-target duplexes, colloidal particles were conjugated with mixtures of probe strands and "diluent" strands in order to minimize the number of DNA linkages between particles. To reduce the steric interference of the diluent strands to hybridization events, diluent strands were clipped with a restriction enzyme in select cases. Kinetics studies revealed that a four to six base-length difference between primary and secondary target strands resulted in extensive competitive hybridization at secondary oligonucleotide concentrations as low as 10 nM. Importantly, it was found that the timing for release of either DNA alone or DNA-conjugated nanoparticles could be tuned through choices in the DNA sequences and concentration. Lastly, competitive hybridization was explored in select studies to drive the "shedding" of PEGylated DNA targets from microspheres to reveal underlying adhesive groups or ligands on the particle surface. Unlike prior work relying on elevated temperatures to melt DNA-linkages, this work presents an important first step towards extending DNA as a reversible assembly tool for physiological applications such as multifunctional drug delivery vehicles programmed to disassemble at targeted tissue sites such as malignant tumors.

Thesis {Ph.D.) -- University of Western Sydney, Nepean, 1998. / Bibliography : p. 328-344.

Thesis (MSc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: see item for full text / AFRIKAANSE OPSOMMING: sien item vir volteks

Orientador: Ítala Maria Loffredo D'Ottaviano / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Filosofia e Ciências Humanas / Made available in DSpace on 2018-08-19T12:55:05Z (GMT). No. of bitstreams: 1 Andrade_RamonSouzaCapelle_D.pdf: 2199404 bytes, checksum: 2cfe6779d4b1e626d3847b217ffd7a7f (MD5) Previous issue date: 2011 / Resumo: O objetivo desta Tese consiste em defender que (a) os condicionais constituem a forma lógica subjacente à manifestação das leis naturais, das leis biológicas e dos hábitos psicocomportamentais. Defendemos, também, que, (b) embora tenhamos a mesma forma lógica subjacente à manifestação dessas regularidades (leis, hábitos), não temos, contudo, o mesmo grau de conexão entre antecedentes e conseqüentes nesses contextos de realidade (físico-químico, biológico e psicocomportamental). Em concordância com a nossa interpretação de parte da Hipótese Cosmológica de Peirce, defendemos que: (c) as leis naturais fortemente determinam seus conseqüentes (Se o antecedente acontece, então o conseqüente quase-necessariamente se segue), (d) as leis biológicas moderadamente determinam seus conseqüentes (Se o antecedente acontece, então o conseqüente muito provavelmente se segue) e (e) os hábitos psicocomportamentais fracamente determinam seus conseqüentes (Se o antecedente acontece, então o conseqüente provavelmente se segue). Anexamos o rótulo Hipótese do Espectro de Determinação de Condicionais Causais a essas diferentes (quase-necessária, muito provável e provável) modalidades de conexão entre antecedentes e conseqüentes. Oferecemos (f), com base na semântica de David Lewis (2005), um modelo para esse espectro de determinação, e procuramos expressar a determinação do condicional e, ao mesmo tempo, deixar espaço para a indeterminação ou acaso. Procuramos (g) caracterizar sistema e organização, e (h) argumentamos que um hábito constitui um componente organizacional da estrutura psicocomportamental de um agente. Oferecemos (i) uma classificação dos hábitos em hábitos que estabelecem os traços da identidade do sistema/agente, hábitos racionais e hábitos degenerados. Procuramos ainda (j) caracterizar a auto-organização e (l) analisar como um processo de auto-organização secundária se estabelece na estrutura psicocomportamental de um agente / Abstract: The objective of this thesis consists in arguing that (a) conditionals constitute the logical form underlying the manifestation of natural laws, biological laws, and psycho-behavioral habits. It is also argued that (b) even though we find the same logical form underlying the manifestation of these regularities (laws and habits), we do not find, however, the same degree of connection between antecedents and consequents in the relevant contexts of reality (physico-chemical, biological, and psycho-behavioral). In accord with our interpretation of part of Peirce's cosmological hypothesis, we argue that (c) natural laws strongly determine their consequents (if the antecedent occurs, then the consequent almost necessarily follows), (d) biological laws moderately determine their consequents (if the antecedent occurs, then the consequent very probably follows), and (e) psycho-behavioral habits weakly determine their consequents (if the antecedent occurs, then the consequent probably follows) We use the appellation "hypothesis of the spectrum of determination of causal conditionals" to express these different modalities of connection between antecedents and consequents (almost-necessary, very probable, and probable). Based on the semantics of David Lewis (2005), we propose (f) a model for this spectrum of determination, and we seek to express the determination of the conditional and, at the same time, to allow room for indetermination or chance. We seek (g) to characterize system and organization, and we argue that (h) a habit constitutes an organizational component in the psycho-behavioral structure of an agent. We offer (i) a threefold classification of habits into habits that establish the features of the identity of the system/agent, rational habits, and degenerate habits. We seek (j) to characterize self-organization, and (k) to analyze how a process of secondary self-organization establishes itself in the psycho-behavioral structure of an agent / Doutorado / Filosofia / Doutor em Filosofia