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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Investigation of supernumerary centrosomes accumulation and Caspase-2 activation in human cell lines

Dzhilyanova, Iva Georgieva 28 February 2022 (has links)
Centrosomes are microtubule-based organelles composed of two centrioles and peri-centriolar material, involved in the formation and organization of the mitotic spindle, serving as microtubule-organizing center and involved in ciliogenesis. Supernumerary centrosomes are detrimental for cell physiology and activate the PIDDosome, a multi-protein complex that serves as a platform for the activation of Caspase-2, composed of: PIDD1, RAIDD and Caspase-2 itself. Caspase-2’s preferred cleavage site based on peptide screening is VDVAD, however Caspase-2, when activated via the PIDDosome, cleaves its bona fide substrate MDM2 (negative p53 regulator) in the FDVPD sequence. Here, I present evidence for VDVADase activity in apoptotic cells lacking Caspase-2, which suggests that this cleavage site is not Caspase-2 specific when the Caspase-2 activation occurs via the PIDDosome. In order to investigate if the mode of activation of Caspase-2 determines its substrate specificities I performed a Caspase-2 rescue experiment and introduced several mutations affecting the Caspase-2 autoproteolytic-processing. Furthermore, I present evidence that exogenous Caspase-2 is able to form the PIDDosome and cleaves MDM2 but when key autoproteolytic sites are mutated no MDM2 cleavage is detectable. Supernumerary centrosomes also accumulate upon overexpression of PLK4 (a kinase regulator of the centriole duplication). Immunofluorescence images of cells overexpressing PLK4 were taken following the centrioles quantification over time. Consequently, a large amount of image data was accumulated, which necessitated the development of a semi-automated pipeline for centrioles counting. This pipeline was generated using the image processing and analysis tool ImageJ and the deep learning segmentation tool MitoS together with the pretrained MitoSegNet model, which was finetuned to count centrioles stained against different centrosomal epitopes, namely Centrin 1, γ-Tubulin and ANKRD26. This semi-automated method of centrioles quantification is easy to use, reproducible and faster than manual quantification. Using this pipeline to quantify centrioles in p53, SCLT1 or ANKRD26 lacking cells we demonstrate accumulation of supernumerary centrosomes in these cells similar to parental cells. / I centrosomi sono organelli cellulari a base di microtubuli, composti da due centrioli e dal materiale pericentriolare che li circonda. I centrosomi sono coinvolti nell'organizzazione dei microtubuli, nella formazione del fuso mitotico e nella ciliogenesi. I centrosomi soprannumerari sono dannosi per la fisiologia cellulare e attivano il PIDDosoma, un complesso multiproteico, composto da PIDD1, RAIDD e Caspasi-2, che funge da piattaforma per l'attivazione della caspasi stessa. Il sito preferenziale di proteolisi di Caspasi-2 è stato individuato tramite screening peptidico nella sequenza VDVAD. Nonostante ciò, quando attivata tramite il PIDDosoma, Caspasi-2 scinde il suo substrato di elezione MDM2 (regolatore negativo di p53) a livello della sequenza FDVPD. In questa tesi presento evidenze di attività VDVAD-asica in cellule apoptotiche prive di Caspasi-2, suggerendo che questo sito di taglio non sia specifico di Caspasi-2 quando la sua attivazione avviene tramite il PIDDosoma. Al fine di indagare se la modalità di attivazione della proteasi determina le sue specificità di substrato, ho eseguito esperimenti di complementazione di Caspasi-2 facendo uso di diversi mutanti che influenzano il suo processamento autoproteolitico. Inoltre, presento prove che Caspasi-2 esogena è in grado di assemblare il PIDDosoma e proteolizzare MDM2 ma quando i suoi siti chiave di autoproteolisi sono mutati non è rilevabile il taglio di MDM2. I centrosomi soprannumerari si accumulano anche in caso di sovraespressione di PLK4 (chinasi regolatrice della duplicazione dei centrioli). Immagini di immunofluorescenza di cellule che sovraesprimono PLK4 sono state acquisite seguendo la cinetica di accumulo dei centrioli nel tempo. Di conseguenza, l’ingente mole di dati generati ha reso necessario lo sviluppo di una procedura semiautomatica per la conta dei centrioli. Questa pipeline è stata generata utilizzando il programma di elaborazione e analisi di immagini ImageJ e il programma di segmentazione basato su deep learning MitoS, insieme al modello MitoSegNet, che è stato affinato per la conta dei centrioli evidenziati tramite immunofluorescenza diretta contro diversi epitopi centrosomiali, ossia: Centrin 1, γ-Tubulina e ANKRD26. Questo metodo semiautomatico di quantificazione dei centrioli è facile da usare, riproducibile e più veloce della quantificazione manuale. Utilizzando questa procedura per quantificare i centrioli nelle cellule prive di p53, SCLT1 o ANKRD26, dimostriamo che l'accumulo di centrosomi soprannumerari in queste cellule è simile a quello riscontrato nelle cellule parentali.
52

Analyse comparative de la terminologie des médias sociaux : contribution des domaines de la communication et de l'informatique à la néologie

Charlebois, Julien-Claude 08 1900 (has links)
L’objectif de cette étude est de repérer des néologismes à partir de corpus de textes français au moyen d’une méthode semi-automatique. Plus précisément, nous extrayons les néologismes de corpus associés à deux domaines différents, mais traitant du même thème, nous examinons leur répartition et nous les classons selon leur type. L’étude s’appuie sur l’analyse de corpus traitant des médias sociaux. Le premier aborde les médias sociaux du point de vue de la communication, l’autre le fait du point de vue de l’informatique. Ces points de vue ont été privilégiés, car la communication considère ce qui a trait l’utilisation des médias sociaux et l’informatique aborde leur cartographie. La méthode fait appel à l’extracteur de termes TermoStat pour recenser la terminologie des médias sociaux pour chaque point de vue. Ensuite, nous soumettons les 150 termes les plus spécifiques de chaque point de vue à une méthode de validation divisée en trois tests destinés à valider leur statut néologique : des dictionnaires spécialisés, des dictionnaires de langue générale et un outil de visualisation de n-grammes. Finalement, nous étiquetons les néologismes selon la typologie de Dubuc (2002). L’analyse des résultats de la communication et de l’informatique est comparative. La comparaison des deux corpus révèle les contributions respectives de la communication et de l'informatique à la terminologie des médias sociaux en plus de montrer les termes communs aux deux disciplines. L’étude a également permis de repérer 60 néologismes, dont 28 sont exclusifs au corpus de la communication, 28 exclusifs à celui de l’informatique et 4 communs aux deux corpus. La recherche révèle également que les composés par subordination sont les types de néologismes les plus présents dans nos résultats. / The objective of this study is to identify the neologisms within corpora of French texts by means of a semi-automatic method. More precisely, we will extract the neologisms from corpora associated to two different areas; however dealing with the same topic, we examine their distribution and we classify them according to their type. This study is based on an analysis of two corpora within social media. The first one approaches social media from the point of view of communication, and the other approaches it from the point of view of computer science. We prioritize these two points of view being that communication is used as the main source of social media’s utilization and that computer science allows us to understand what is involved to allow for social media to be functional. For this method, we use the TermoStat term extractor in order to take census of terminology for each point of view. We then submit 150 of the most specific terms related to each point of view by way of an exclusion corpus from which we divide into three different tests meant to validate their neological status: specialized dictionaries, general language dictionaries, and a visualization tool for n-grams. Lastly, we label the neologisms according to Dubuc’s (2002) typology. The analysis of the results obtained for communication and computer science uses a comparative method. The comparison of the two corpora reveals the respective contributions from communication and computer science with respect to the terminology of social medias, as well it demonstrates common terms found within the two disciplines. This examination also allowed for the identification of 60 neologisms; of which 28 are exclusive to the corpus of communication, another 28 are exclusive to that of computer science, and four were found to be common to both corpora. This research also reveals that subordinate compounds are the most present types of neologisms according to our results.
53

Anisotropie svrchního pláště pod Severními Apeninami z dat mezinárodního experimentu RETREAT (Itálie) / Anisotropie svrchního pláště pod Severními Apeninami z dat mezinárodního experimentu RETREAT (Itálie)

Munzarová, Helena January 2011 (has links)
Title: Anisotropy of the upper mantle under the Northern Apennines based on data from the international experiment RETREAT (Italy) Author: Helena Munzarová Department: Department of Geophysics Supervisor of the master thesis: RNDr. František Gallovič, Ph.D. Department of Geophysics Consultant of the master thesis: RNDr. Jaroslava Plomerová, DrSc. Institute of Geophysics, Czech Academy of Sciences Abstract: In this master thesis, we process data recorded during the passive seismic experiment RETREAT (2003-2006) in the Northern Apennines with the aim to explore the upper mantle structure in the region. Active orogeny in the Northern Apennines relates to the collision of the Tyrrhenian and Adriatic (subducting westward) plates and is accompanied by an eastward retreat of the trench. Directional dependences of P-wave travel-time deviations together with variations of the fast split polarization azimuths of teleseismic SKS waves are derived from data recorded during experiment RETREAT. Both the fossil anisotropic structure in the mantle lithosphere and the anisotropy due to the present-day flow in the sub-lithospheric mantle are sources of the observed velocity-anisotropy patterns. Thick continental Adriatic plate can be divided into at least two sub-regions with their own fossil fabrics. We have also tried to...
54

Separating Tweets from Croaks : Detecting Automated Twitter Accounts with Supervised Learning and Synthetically Constructed Training Data / : Automationsdetektion av Twitter-konton med övervakad inlärning och syntetiskt konstruerad träningsmängd

Teljstedt, Erik Christopher January 2016 (has links)
In this thesis, we have studied the problem of detecting automated Twitter accounts related to the Ukraine conflict using supervised learning. A striking problem with the collected data set is that it was initially lacking a ground truth. Traditionally, supervised learning approaches rely on manual annotation of training sets, but it incurs tedious work and becomes expensive for large and constantly changing collections. We present a novel approach to synthetically generate large amounts of labeled Twitter accounts for detection of automation using a rule-based classifier. It significantly reduces the effort and resources needed and speeds up the process of adapting classifiers to changes in the Twitter-domain. The classifiers were evaluated on a manually annotated test set of 1,000 Twitter accounts. The results show that rule-based classifier by itself achieves a precision of 94.6% and a recall of 52.9%. Furthermore, the results showed that classifiers based on supervised learning could learn from the synthetically generated labels. At best, the these machine learning based classifiers achieved a slightly lower precision of 94.1% compared to the rule-based classifier, but at a significantly better recall of 93.9% / Detta exjobb har undersökt problemet att detektera automatiserade Twitter-konton relaterade till Ukraina-konflikten genom att använda övervakade maskininlärningsmetoder. Ett slående problem med den insamlade datamängden var avsaknaden av träningsexempel. I övervakad maskininlärning brukar man traditionellt manuellt märka upp en träningsmängd. Detta medför dock långtråkigt arbete samt att det blir dyrt förstora och ständigt föränderliga datamängder. Vi presenterar en ny metod för att syntetiskt generera uppmärkt Twitter-data (klassifieringsetiketter) för detektering av automatiserade konton med en regel-baseradeklassificerare. Metoden medför en signifikant minskning av resurser och anstränging samt snabbar upp processen att anpassa klassificerare till förändringar i Twitter-domänen. En utvärdering av klassificerare utfördes på en manuellt uppmärkt testmängd bestående av 1,000 Twitter-konton. Resultaten visar att den regelbaserade klassificeraren på egen hand uppnår en precision på 94.6% och en recall på 52.9%. Vidare påvisar resultaten att klassificerare baserat på övervakad maskininlärning kunde lära sig från syntetiskt uppmärkt data. I bästa fall uppnår dessa maskininlärningsbaserade klassificerare en något lägre precision på 94.1%, jämfört med den regelbaserade klassificeraren, men med en betydligt bättre recall på 93.9%.
55

Statistical determination of atomic-scale characteristics of nanocrystals based on correlative multiscale transmission electron microscopy

Neumann, Stefan 21 December 2023 (has links)
The exceptional properties of nanocrystals (NCs) are strongly influenced by many different characteristics, such as their size and shape, but also by characteristics on the atomic scale, such as their crystal structure, their surface structure, as well as by potential microstructure defects. While the size and shape of NCs are frequently determined in a statistical manner, atomic-scale characteristics are usually quantified only for a small number of individual NCs and thus with limited statistical relevance. Within this work, a characterization workflow was established that is capable of determining relevant NC characteristics simultaneously in a sufficiently detailed and statistically relevant manner. The workflow is based on transmission electron microscopy, networked by a correlative multiscale approach that combines atomic-scale information on NCs obtained from high-resolution imaging with statistical information on NCs obtained from low-resolution imaging, assisted by a semi-automatic segmentation routine. The approach is complemented by other characterization techniques, such as X-ray diffraction, UV-vis spectroscopy, dynamic light scattering, or alternating gradient magnetometry. The general applicability of the developed workflow is illustrated on several examples, i.e., on the classification of Au NCs with different structures, on the statistical determination of the facet configurations of Au nanorods, on the study of the hierarchical structure of multi-core iron oxide nanoflowers and its influence on their magnetic properties, and on the evaluation of the interplay between size, morphology, microstructure defects, and optoelectronic properties of CdSe NCs.:List of abbreviations and symbols 1 Introduction 1.1 Types of nanocrystals 1.2 Characterization of nanocrystals 1.3 Motivation and outline of this thesis 2 Materials and methods 2.1 Nanocrystal synthesis 2.1.1 Au nanocrystals 2.1.2 Au nanorods 2.1.3 Multi-core iron oxide nanoparticles 2.1.4 CdSe nanocrystals 2.2 Nanocrystal characterization 2.2.1 Transmission electron microscopy 2.2.2 X-ray diffraction 2.2.3 UV-vis spectroscopy 2.2.3.1 Au nanocrystals 2.2.3.2 Au nanorods 2.2.3.3 CdSe nanocrystals 2.2.4 Dynamic light scattering 2.2.5 Alternating gradient magnetometry 2.3 Methodical development 2.3.1 Correlative multiscale approach – Statistical information beyond size and shape 2.3.2 Semi-automatic segmentation routine 3 Classification of Au nanocrystals with comparable size but different morphology and defect structure 3.1 Introduction 3.1.1 Morphologies and structures of Au nanocrystals 3.1.2 Localized surface plasmon resonance of Au nanocrystals 3.1.3 Motivation and outline 3.2 Results 3.2.1 Microstructural characteristics of the Au nanocrystals 3.2.2 Insufficiency of two-dimensional size and shape for an unambiguous classification of the Au nanocrystals 3.2.3 Statistical classification of the Au nanocrystals 3.2.4 Advantage of a multidimensional characterization of the Au nanocrystals 3.2.5 Estimation of the density of planar defects in the Au nanoplates 3.3 Discussion 3.4 Conclusions 4 Statistical determination of the facet configurations of Au nanorods 4.1 Introduction 4.1.1 Growth mechanism and facet formation of Au nanorods 4.1.2 Localized surface plasmon resonance of Au nanorods 4.1.3 Catalytic activity of Au nanorods 4.1.4 Motivation and outline 4.2 Results 4.2.1 Statistical determination of the size and shape of the Au nanorods 4.2.2 Microstructural characteristics and facet configurations of the Au nanorods 4.2.3 Statistical determination of the facet configurations of the Au nanorods 4.3 Discussion 4.4 Conclusions 5 Influence of the hierarchical architecture of multi-core iron oxide nanoflowers on their magnetic properties 5.1 Introduction 5.1.1 Phase composition and phase distribution in iron oxide nanoparticles 5.1.2 Magnetic properties of iron oxide nanoparticles 5.1.3 Mono-core vs. multi-core iron oxide nanoparticles 5.1.4 Motivation and outline 5.2 Results 5.2.1 Phase composition, vacancy ordering, and antiphase boundaries 5.2.2 Arrangement and coherence of individual cores within the iron oxide nanoflowers 5.2.3 Statistical determination of particle, core, and shell size 5.2.4 Influence of the coherence of the cores on the magnetic properties 5.3 Discussion 5.4 Conclusions 6 Interplay between size, morphology, microstructure defects, and optoelectronic properties of CdSe nanocrystals 6.1 Introduction 6.1.1 Polymorphism in CdSe nanocrystals 6.1.2 Optoelectronic properties of CdSe nanocrystals 6.1.3 Nucleation, growth, and coarsening of CdSe nanocrystals 6.1.4 Motivation and outline 6.2 Results 6.2.1 Influence of the synthesis temperature on the optoelectronic properties of the CdSe nanocrystals 6.2.2 Microstructural characteristics of the CdSe nanocrystals 6.2.3 Statistical determination of size, shape, and amount of oriented attachment of the CdSe nanocrystals 6.3 Discussion 6.4 Conclusions 7 Summary and outlook References Publications
56

Oorsake van leermislukking in die junior primêre fase van skole in die Windhoek stadsgebied / Causes of learning failure in the junior primary school phase in the Windhoek municipal area

Cloete Hendrika 11 1900 (has links)
Text in Afrikaans / Die doel van hierdie ondersoek is om die ekstrinsieke en intrinsieke oorsake van leermislukking met spesifieke verwysing na skole in die Windhoek stadsgebied te bepaal en om aanbevelings te doen hoe om leermislukking teen te werk. Leermislukking en druiping is onrusbarend hoog in skole in die Windhoek stadsgebied. Nadat die Ministerie van Onderwys die semi-outomatiese promoveringstelsel ingestel het, het druiping afgeneem maar leermislukking het toegeneem omdat leerders gepromoveer word sander dat hulle sukses in die vorige graad behaal het. Volgens die literatuurstudie lê die oorsake van leermislukking by die ouerhuis, die skool, die omgewing en in die leerder self. Die empiriese ondersoek toon ooreenkomste met die literatuurstudie wat betref die oorsake van leermislukking. Om die oorsake teen te werk • moet onderwysers beter opgelei word • moet die ouers meer bewus gemaak word van hulle rot in die leersukses van hulle kinders. • is meer skoolgeboue en onderwysers nodig om kleiner klasse te bewerkstellig. / The purpose of this research is to establish the extrinsic and intrinsic causes of learning failure with specific reference to schools in the Windhoek municipal area and to make recommendations to counteract learning failure. Learning failure and grade failing are disconcertingly high in schools in the Windhoek municipal area. After the Ministry of Education implemented the semi-automatic promotion system, grade failing decreased, but learning failure increased because learners are promoted without achieving success in a prior grade. According to the literature study, the causes of learning failure are to be found in the home, the school, the environment, and the learner. Similarities regarding the causes of learning failure were found in the empirical investigation and the literature study. To counteract these causes • teachers should be better trained • parents should become more aware of their role in the learning success of their children • more school buildings and teachers are needed to limit class sizes. / Educational Studies / M. Ed. (Spesiale Behoeftes Onderwys)
57

Oorsake van leermislukking in die junior primêre fase van skole in die Windhoek stadsgebied / Causes of learning failure in the junior primary school phase in the Windhoek municipal area

Cloete Hendrika 11 1900 (has links)
Text in Afrikaans / Die doel van hierdie ondersoek is om die ekstrinsieke en intrinsieke oorsake van leermislukking met spesifieke verwysing na skole in die Windhoek stadsgebied te bepaal en om aanbevelings te doen hoe om leermislukking teen te werk. Leermislukking en druiping is onrusbarend hoog in skole in die Windhoek stadsgebied. Nadat die Ministerie van Onderwys die semi-outomatiese promoveringstelsel ingestel het, het druiping afgeneem maar leermislukking het toegeneem omdat leerders gepromoveer word sander dat hulle sukses in die vorige graad behaal het. Volgens die literatuurstudie lê die oorsake van leermislukking by die ouerhuis, die skool, die omgewing en in die leerder self. Die empiriese ondersoek toon ooreenkomste met die literatuurstudie wat betref die oorsake van leermislukking. Om die oorsake teen te werk • moet onderwysers beter opgelei word • moet die ouers meer bewus gemaak word van hulle rot in die leersukses van hulle kinders. • is meer skoolgeboue en onderwysers nodig om kleiner klasse te bewerkstellig. / The purpose of this research is to establish the extrinsic and intrinsic causes of learning failure with specific reference to schools in the Windhoek municipal area and to make recommendations to counteract learning failure. Learning failure and grade failing are disconcertingly high in schools in the Windhoek municipal area. After the Ministry of Education implemented the semi-automatic promotion system, grade failing decreased, but learning failure increased because learners are promoted without achieving success in a prior grade. According to the literature study, the causes of learning failure are to be found in the home, the school, the environment, and the learner. Similarities regarding the causes of learning failure were found in the empirical investigation and the literature study. To counteract these causes • teachers should be better trained • parents should become more aware of their role in the learning success of their children • more school buildings and teachers are needed to limit class sizes. / Educational Studies / M. Ed. (Spesiale Behoeftes Onderwys)
58

Génération automatique de phrases pour l'apprentissage des langues / Natural language generation for language learning

Perez, Laura Haide 19 April 2013 (has links)
Dans ces travaux, nous explorons comment les techniques de Générations Automatiques de Langue Naturelle (GLN) peuvent être utilisées pour aborder la tâche de génération (semi-)automatique de matériel et d'activités dans le contexte de l'apprentissage de langues assisté par ordinateur. En particulier, nous montrons comment un Réalisateur de Surface (RS) basé sur une grammaire peut être exploité pour la création automatique d'exercices de grammaire. Notre réalisateur de surface utilise une grammaire réversible étendue, à savoir SemTAG, qui est une Grammaire d'Arbre Adjoints à Structure de Traits (FB-TAG) couplée avec une sémantique compositionnelle basée sur l'unification. Plus précisément, la grammaire FB-TAG intègre une représentation plate et sous-spécifiée des formules de Logique de Premier Ordre (FOL). Dans la première partie de la thèse, nous étudions la tâche de réalisation de surface à partir de formules sémantiques plates et nous proposons un algorithme de réalisation de surface basé sur la grammaire FB-TAG optimisé, qui supporte la génération de phrases longues étant donné une grammaire et un lexique à large couverture. L'approche suivie pour l'optimisation de la réalisation de surface basée sur FB-TAG à partir de sémantiques plates repose sur le fait qu'une grammaire FB-TAG peut être traduite en une Grammaire d'Arbres Réguliers à Structure de Traits (FB-RTG) décrivant ses arbres de dérivation. Le langage d'arbres de dérivation de la grammaire TAG constitue un langage plus simple que le langage d'arbres dérivés, c'est pourquoi des approches de génération basées sur les arbres de dérivation ont déjà été proposées. Notre approche se distingue des précédentes par le fait que notre encodage FB-RTG prend en compte les structures de traits présentes dans la grammaire FB-TAG originelle, ayant de ce fait des conséquences importantes par rapport à la sur-génération et la préservation de l'interface syntaxe-sémantique. L'algorithme de génération d'arbres de dérivation que nous proposons est un algorithme de type Earley intégrant un ensemble de techniques d'optimisation bien connues: tabulation, partage-compression (sharing-packing) et indexation basée sur la sémantique. Dans la seconde partie de la thèse, nous explorons comment notre réalisateur de surface basé sur SemTAG peut être utilisé pour la génération (semi-)automatique d'exercices de grammaire. Habituellement, les enseignants éditent manuellement les exercices et leurs solutions et les classent au regard de leur degré de difficulté ou du niveau attendu de l'apprenant. Un courant de recherche dans le Traitement Automatique des Langues (TAL) pour l'apprentissage des langues assisté par ordinateur traite de la génération (semi-)automatique d'exercices. Principalement, ces travaux s'appuient sur des textes extraits du Web, utilisent des techniques d'apprentissage automatique et des techniques d'analyse de textes (par exemple, analyse de phrases, POS tagging, etc.). Ces approches confrontent l'apprenant à des phrases qui ont des syntaxes potentiellement complexes et du vocabulaire varié. En revanche, l'approche que nous proposons dans cette thèse aborde la génération (semi-)automatique d'exercices du type rencontré dans les manuels pour l'apprentissage des langues. Il s'agit, en d'autres termes, d'exercices dont la syntaxe et le vocabulaire sont faits sur mesure pour des objectifs pédagogiques et des sujets donnés. Les approches de génération basées sur des grammaires associent les phrases du langage naturel avec une représentation linguistique fine de leur propriété morpho-syntaxiques et de leur sémantique grâce à quoi il est possible de définir un langage de contraintes syntaxiques et morpho-syntaxiques permettant la sélection de phrases souches en accord avec un objectif pédagogique donné. Cette représentation permet en outre d'opérer un post-traitement des phrases sélectionées pour construire des exercices de grammaire / In this work, we explore how Natural Language Generation (NLG) techniques can be used to address the task of (semi-)automatically generating language learning material and activities in Camputer-Assisted Language Learning (CALL). In particular, we show how a grammar-based Surface Realiser (SR) can be usefully exploited for the automatic creation of grammar exercises. Our surface realiser uses a wide-coverage reversible grammar namely SemTAG, which is a Feature-Based Tree Adjoining Grammar (FB-TAG) equipped with a unification-based compositional semantics. More precisely, the FB-TAG grammar integrates a flat and underspecified representation of First Order Logic (FOL) formulae. In the first part of the thesis, we study the task of surface realisation from flat semantic formulae and we propose an optimised FB-TAG-based realisation algorithm that supports the generation of longer sentences given a large scale grammar and lexicon. The approach followed to optimise TAG-based surface realisation from flat semantics draws on the fact that an FB-TAG can be translated into a Feature-Based Regular Tree Grammar (FB-RTG) describing its derivation trees. The derivation tree language of TAG constitutes a simpler language than the derived tree language, and thus, generation approaches based on derivation trees have been already proposed. Our approach departs from previous ones in that our FB-RTG encoding accounts for feature structures present in the original FB-TAG having thus important consequences regarding over-generation and preservation of the syntax-semantics interface. The concrete derivation tree generation algorithm that we propose is an Earley-style algorithm integrating a set of well-known optimisation techniques: tabulation, sharing-packing, and semantic-based indexing. In the second part of the thesis, we explore how our SemTAG-based surface realiser can be put to work for the (semi-)automatic generation of grammar exercises. Usually, teachers manually edit exercises and their solutions, and classify them according to the degree of dificulty or expected learner level. A strand of research in (Natural Language Processing (NLP) for CALL addresses the (semi-)automatic generation of exercises. Mostly, this work draws on texts extracted from the Web, use machine learning and text analysis techniques (e.g. parsing, POS tagging, etc.). These approaches expose the learner to sentences that have a potentially complex syntax and diverse vocabulary. In contrast, the approach we propose in this thesis addresses the (semi-)automatic generation of grammar exercises of the type found in grammar textbooks. In other words, it deals with the generation of exercises whose syntax and vocabulary are tailored to specific pedagogical goals and topics. Because the grammar-based generation approach associates natural language sentences with a rich linguistic description, it permits defining a syntactic and morpho-syntactic constraints specification language for the selection of stem sentences in compliance with a given pedagogical goal. Further, it allows for the post processing of the generated stem sentences to build grammar exercise items. We show how Fill-in-the-blank, Shuffle and Reformulation grammar exercises can be automatically produced. The approach has been integrated in the Interactive French Learning Game (I-FLEG) serious game for learning French and has been evaluated both based in the interactions with online players and in collaboration with a language teacher
59

Identificação de possíveis áreas afetadas por sais no Perímetro Irrigado de São Gonçalo por meio do sensoriamento remoto. / Identification of possible areas affected by salts in the Irrigated Perimeter of São Gonçalo through remote sensing

OLIVEIRA, Woslley Sidney Nogueira de. 10 May 2018 (has links)
Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-05-10T18:06:15Z No. of bitstreams: 1 WOSLLEY SIDNEY NOGUEIRA DE OLIVEIRA - DISSERTAÇÃO PPGSA ACADÊMICO 2018..pdf: 7059892 bytes, checksum: 1ab51771320e5bbd6c88d3c01b4b7aeb (MD5) / Made available in DSpace on 2018-05-10T18:06:15Z (GMT). No. of bitstreams: 1 WOSLLEY SIDNEY NOGUEIRA DE OLIVEIRA - DISSERTAÇÃO PPGSA ACADÊMICO 2018..pdf: 7059892 bytes, checksum: 1ab51771320e5bbd6c88d3c01b4b7aeb (MD5) Previous issue date: 2018-02-22 / Os perímetros irrigados implantados no Estado da Paraíba são considerados uma alternativa econômica bastante rentável, promove a geração de empregos e aumenta a disponibilidade de alimentos. Devido ao manejo inadequado do solo e da água, isso têm causado perdas na qualidade do solo desses perímetros, degradando-os principalmente por salinização. O sensoriamento remoto é uma alternativa tecnológica de baixo custo, boa frequência temporal e possui a capacidade de mapear áreas em processo de desertificação. Essa pesquisa têm por objetivo identificar possíveis áreas afetadas por sais no Perímetro Irrigado de São Gonçalo (PISG), Sousa- PB, por meio de técnicas de sensoriamento remoto. Para esse estudo foi utilizado imagens do satélite LANDSAT 8/OLI (média resolução espacial), órbita 216 / ponto 65 da data de 23/11/2016; imagem do software Google Earth Pro® da data de 29/02/2016 para servir como imagem auxiliar e registros fotográficos das áreas in loco. Realizou-se a técnica de classificação supervisionada, utilizando o SCP (semi- automatic plugin) no software QGIS (Quantum Gis). A aferição da qualidade da classificação se deu por meio da validação cruzada, utilizando de parâmetros estatísticos como a exatidão do produtor (EP), exatidão do usuário (EU), exatidão global (EG) e índice Kappa. A classe área supostamente salinizada (ASS) apresentou EP e EU de 89.15% e 88.88%, respectivamente. O índice Kappa resultou em um valor de 0.8684, a classe ASS foi classificada como sendo de qualidade excelente. A qualidade geral da classificação é avaliada tanto pela EG que apresentou um valor de 0.9350 como pelo índice Kappa geral com valor de 0.9252, sendo valores que representam uma classificação de qualidade excelente. A classe ASS apresentou os maiores valores mínimos e máximos de fator de refletância em todas as bandas da imagem, destacando a banda 6 de valores 0.47 e 0.67, respectivamente. O valor da área classificada como sendo da classe ASS foi de 1736.75 hectares, 31% da área total do PISG. As imagens analisadas possibilitaram discriminar áreas salinizadas e não salinizadas mediante as diferenças de tonalidade e de refletância. As imagens analisadas com o plugin SCP possibilitaram a realização de um mapa de classificação supervisionada, indicando a variabilidade espacial das áreas propícias ao processo de salinização. No entanto, recomenda- se a análise dos parâmetros físicos e químicos do solo dessas áreas para o aumento da confiabilidade na qualidade desse tipo de mapeamento. / The irrigated perimeters implemented in the State of Paraiba are considered a costeffective alternative quite profitable, promotes the generation of jobs and increases the availability of food. Due to inadequate management of soil and water, that have caused losses in soil quality of these perimeters, degrading them mainly by salinization. Remote sensing is an alternative low-cost technology, good temporal and frequency has the ability to map areas in process of desertification. This research aim to identify potential areas affected by salts in the irrigated perimeter of São Gonçalo (PISG), Sousa-PB, through remote sensing techniques. For this study we used LANDSAT satellite images 8/OLI (average spatial resolution), 216/orbit point 65 of 07/11/2016 date; image of the Google Earth Pro software® from date of 29/02/2016 to serve as auxiliary image and photographic records of the areas on the spot. The supervised classification technique, using the SCP (semi-automatic plugin) in software QGIS (Quantum Gis). The measurement of the quality of the classification took place by means of cross-validation, using statistical parameters such as the accuracy of the producer (EP), accuracy of the user (EU), global (EG) accuracy and Kappa index. The area class supposedly salinated (.ASS) presented EP and I of 89.15% and 88.88%, respectively. The Kappa index resulted in a value of .ASS class 0.8684 was classified as being of excellent quality. The overall quality of the classification is assessed both by EG who presented a 0.9350 value as the Kappa index 0.9252 valued General, being values that represent a rating of excellent quality. The class ASS presented the largest minimum and maximum values of reflectance factor in all the bands in the image, highlighting the band 6 0.47 values and 0.67, respectively. The value of the area classified as being of .ASS class was 1736.75 acres, 31% of the total area of the PISG. The images reviewed discriminate salinated areas and not allowed saline through the variations of shade and reflectance. The images analyzed with the SCP plugin enabled the creation of a map of supervised classification, indicating the spatial variability of the areas prone to salinization process. However, it is recommended that the analysis of the physical and chemical soil parameters of these areas for increased reliability in the quality of this type of mapping.

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