Grounding human vocabulary in robot perception through interaction

This thesis addresses the problem of word learning in computational agents. The motivation behind this work lies in the need to support language-based communication between service robots and their human users, as well as grounded reasoning using symbols relevant for the assigned tasks. The research focuses on the problem of grounding human vocabulary in robotic agent’s sensori-motor perception. Words have to be grounded in bodily experiences, which emphasizes the role of appropriate embodiments. On the other hand, language is a cultural product created and acquired through social interactions. This emphasizes the role of society as a source of linguistic input. Taking these aspects into account, an experimental scenario is set up where a human instructor teaches a robotic agent the names of the objects present in a visually shared environment. The agent grounds the names of these objects in visual perception. Word learning is an open-ended problem. Therefore, the learning architecture of the agent will have to be able to acquire words and categories in an openended manner. In this work, four learning architectures were designed that can be used by robotic agents for long-term and open-ended word and category acquisition. The learning methods used in these architectures are designed for incrementally scaling-up to larger sets of words and categories. A novel experimental evaluation methodology, that takes into account the openended nature of word learning, is proposed and applied. This methodology is based on the realization that a robot’s vocabulary will be limited by its discriminatory capacity which, in turn, depends on its sensors and perceptual capabilities. An extensive set of systematic experiments, in multiple experimental settings, was carried out to thoroughly evaluate the described learning approaches. The results indicate that all approaches were able to incrementally acquire new words and categories. Although some of the approaches could not scale-up to larger vocabularies, one approach was shown to learn up to 293 categories, with potential for learning many more.

Diversity of Aeromonas species from different environments in Portugal

Espécies de Aeromonas encontram-se distribuídas por diferentes habitats, estando especialmente relacionadas com ambientes aquáticos. O seu papel em complicações na saúde humana e animal é reconhecido. De facto, não só pelo seu potencial de virulência, mas também pelos determinantes genéticos de resistência a antibióticos que possam conter, estes organismos constituem uma preocupação na medicina humana e veterinária. Assim, é essencial o estudo da diversidade de espécies de Aeromonas bem como explorar as suas características fenotípicas e genéticas que podem conduzir a impactos negativos. A água constitui um importante veículo de transmissão de microrganismos e espécies de Aeromonas estão amplamente distribuídas em águas tratadas e não tratadas. Em Portugal é ainda comum o consumo de águas não tratadas cuja qualidade, na maioria das vezes, não é sujeita a monitorização, como acontece por exemplo, em explorações agrícolas de gestão familiar. Neste estudo, investigou-se a presença de Aeromonas em águas não tratadas para consumo. Estabeleceu-se também uma linha horizontal de colheitas de diferentes amostras de origem agrícola com o intuito de avaliar a possibilidade de a água ser uma das vias de contaminação de culturas agrícolas e animais por espécies de Aeromonas. Obtiveram-se 483 isolados que foram discriminados por RAPD-PCR. 169 estirpes distintas foram identificadas ao nível da espécie por análise filogenética baseada no gene gyrB. Verificou-se uma frequente ocorrência bem como uma diversidade considerável de espécies de Aeromonas. Em alguns casos, as relações genotípicas entre isolados de diferentes amostras eram muito próximas. Adicionalmente, a maioria das amostras continha diferentes espécies e estirpes distintas da mesma espécie. A. media e A. hydrophila foram as espécies mais ocorrentes. Um grupo de isolados apresentou variantes moleculares de gyrB diferente das conhecidas até agora, o que indica que poderão constituir espécies não descritas. O perfil de susceptibilidade da colecção de Aeromonas a diferentes antibióticos foi estabelecido, constituindo um perfil típico do género, com algumas excepções. Estirpes multirresistentes foram encontradas. A presença de genes tet e bla foi investigada por estudos de PCR, hibridação e, em alguns casos, de sequenciação. Como era esperado, cphA/imiS foi o mais detectado. A detecção de integrões fez-se por PCR e hibridação e a sua caracterização foi feita por sequenciação de DNA; a sua ocorrência foi reduzida. A maioria das estirpes sintetizou enzimas extracelulares com actividade lipolítica e proteolítica que potencialmente contribuem para virulência. A análise por PCR e hibridação permitiram a detecção de vários determinantes genéticos que codificam moléculas possivelmente envolvidas em processos patogénicos. Diversas espécies de Aeromonas apresentando características relacionadas com resistência a antibióticos e potencialmente de virulência estão frequentemente presentes em produtos para consumo humano e animal em Portugal. ABSTRACT: Aeromonas spp. are present in a wide range of ecological niches, being mainly related to aquatic environments. Their role in human and animal health complications is recognised. In fact, not only for their putative virulence but also for the antibiotic resistance genetic determinants Aeromonas may harbour, these organisms constitute an issue of concern in human and veterinary medicine. Thus, it is essential to get knowledge on Aeromonas sp. diversity and on their genotypic and phenotypic characteristics that may lead to negative impacts. Water constitutes a good contamination route for microorganisms and Aeromonas are widespread in untreated and treated waters from different sources. In Portugal there is still an extensive use of untreated water which is not regularly monitored for quality. This is often the case in family smallholding farms. In this study untreated drinking and mineral waters were assessed for their content in Aeromonas spp. Furthermore, a sampling scheme was designed to investigate the occurrence and diversity of Aeromonas sp. in different agricultural correlated sources and to assess the possibility of water being the transmission vehicle between those sources. 483 isolates were obtained and discriminated by RAPD-PCR. Identification at the species level for 169 distinct strains was done by gyrB based phylogenetic analysis. Results demonstrated the frequent occurrence and considerable diversity of Aeromonas spp. In some cases, genotypic close relations were found between isolates from different sources. Also, most samples contained different species and distinct strains of the same species. A. media and A. hydrophila were the most occurring. A group of isolates displayed gyrB gene sequences distinct from the previously known, indicating that they may constitute representatives of non-described species. The antibiotic susceptibility profile of the aeromonads collection was established and constituted a typical profile of the genus, although few exceptions. Multiresistance patterns were found. The presence of tet and bla genes was investigated by PCR, hybridisation and, in some cases, sequencing analysis. As expected, cphA/imiS was the most detected. Integrons were screened by PCR and hybridisation and characterised by DNA sequencing; low occurrence was recorded. The bulk of strains was able to produce extracellular enzymes with lipolytic and proteolytic activities, which may contribute to virulence. PCR and hybridisation surveys allowed the detection of distinct genetic determinants coding for molecules putatively involved in pathogenic processes. Diverse Aeromonas sp. presenting distinct antibiotic resistance features and putative virulence traits are frequently present in many sources for human and animal consumption in Portugal.