Thesis (Ph.D.)--University of Florida, 2004. / Typescript. Title from title page of source document. Document formatted into pages; contains 87 pages. Includes Vita. Includes bibliographical references.

Οι μηχανές αναζήτησης είναι ένα ανεκτίμητο εργαλείο για την ανάκτηση πληροφοριών από το διαδίκτυο. Απαντώντας στα ερωτήματα του χρήστη, επιστρέφουν μια λίστα με αποτελέσματα, ταξινομημένα κατά σειρά, με βάση τη συνάφεια του περιεχομένου τους προς το ερώτημα. Ωστόσο, αν και οι μηχανές αναζήτησης είναι σίγουρα αρκετά καλές στην αναζήτηση συγκεκριμένων ερωτημάτων, όπως είναι η εύρεση μιας συγκεκριμένης ιστοσελίδας, αντίθετα μπορούν να είναι λιγότερο αποτελεσματικές όσον αφορά την αναζήτηση ασαφών, προς αυτές, ερωτημάτων, όπως για παράδειγμα όταν συναντούμε το φαινόμενο της αμφισημίας, όπου μια λέξη μπορεί να πάρει περισσότερες από μία έννοιες μέσα στα συμφραζόμενα διαφορετικής πρότασης. Άλλο ένα παράδειγμα ερωτήματος είναι όταν υπάρχουν περισσότερες από δύο υποκατηγορίες και νοήματα σ’ ένα ερώτημα, πράγμα που σημαίνει ότι ο χρήστης θα πρέπει να διατρέξει έναν μεγάλο αριθμό αποτελεσμάτων για να βρει αυτά που τον ενδιαφέρουν. Στόχος της παρούσας διπλωματικής εργασίας είναι η ανάπτυξη ενός έμπειρου συστήματος, που θα μετά-επεξεργάζεται τις απαντήσεις μας κλασικής μηχανής αναζήτησης και θα ομαδοποιεί τα αποτελέσματα σε μια ιεραρχία από κατηγορίες με βάση το περιεχόμενο τους. Οι σημαντικότερες σημερινές λύσεις πάνω στο πρόβλημα της αντιστοίχησης των αποτελεσμάτων σε συστάδες είναι τα συστήματα Vivisimo, Carrot, CREDO και SnakeT. Η συνεισφορά που προτείνεται στη παρούσα εργασία, είναι η χρήση μίας σειράς τεχνικών που βελτιώνουν την ποιότητα των ομάδων απάντησης. Μία πρωτότυπη τεχνική που χρησιμοποιήθηκε στην παρούσα εργασία είναι η αναδιατύπωση των ερωτημάτων (query reformulation) μέσω διαφόρων στρατηγικών. Ο λόγος που παρουσιάζονται τέτοιες στρατηγικές, είναι επειδή συχνά οι χρήστες τροποποιούν ένα προηγούμενο ερώτημα αναζήτησης ώστε να ανακτήσουν καλύτερα αποτελέσματα ή κι επειδή πολλές φορές δεν μπορούν να διατυπώσουν σωστά ένα ερώτημα λόγω της μη γνώσης επιθυμητών αποτελεσμάτων. Επιπλέον, επωφεληθήκαμε από τη Wikipedia αντλώντας δεδομένα από τους τίτλους των σελίδων αλλά κι από τις κατηγορίες στις οποίες ανήκουν αυτές οι σελίδες. Αυτό γίνεται μέσω της σύνδεσης των συχνών όρων που ανήκουν στα κείμενα των αποτελεσμάτων αναζήτησης με τη σημασιολογική εγκυκλοπαίδεια Wikipedia, με σκοπό την εξαγωγή των διαφορετικών εννοιών και νοημάτων του κάθε όρου. Ειδικότερα, αναζητείται στη Wikipedia η ύπαρξη σελίδας (ή σελίδων για το φαινόμενο της αμφισημίας) που αντιστοιχίζονται στους όρους αυτούς με αποτέλεσμα τη χρησιμοποίηση του τίτλου και της κατηγορίας ως επιπρόσθετη πληροφορία. Τέλος η Wikipedia χρησιμοποιείται και στην ανάθεση ετικετών στις τελικές συστάδες ως επιπρόσθετη πληροφορία κάθε ξεχωριστού κειμένου που βρίσκεται στη συστάδα. / -

Titel: Ett Färgat Köpbeteende Nivå: C-uppsats i ämnet företagsekonomi Författare: Martin Myhrman & Robin Uppman Handledare: Jonas KågströmDatum: 2015 - 05 Syfte: Bakgrunden till att vi har utfört denna studie är att forskning om färgers påverkan på beslutsfattande inom ämnet marknadsföring är begränsad, tidigare forskning har även pekat på att vidare forskning borde beröra vilka faktorer som skulle kunna påverka konsumenters uppfattning om genmodifierade produkter. Således är vårt syfte:“Syftet med denna uppsats är att undersöka hur färgkodad märkning kan kompensera för den negativa uppfattningen som kan råda kring genmodifierade livsmedel.” Metod: För att besvara vårt syfte har vi valt att utföra ett experiment. Studien genomfördes på 120 respondenter på en högskola i Sverige, testpersonerna utförde ett smaktest där de tre olika betingelserna var märkta med olika färger (röd, blå och grön). Den data vi fick in analyserades sedan med hjälp av statistikprogrammet IBM SPSS Statistics 22, därefter har vi tolkat och diskuterat resultaten. Resultat & Slutsats: Vårt huvudsakliga fynd är att röd färg på negativ märkning genererar lägre betalningsvilja än grön och blå färg, vårt resultat korroborerar tidigare forskning som bland annat menar att röd färg bidrar till en aggressivare sinnesstämning och ett mer analytiskt tänkande. I övrigt har vi sett tendenser till att färgen på märkningen inte påverkat varken smakupplevelsen eller hälsouppfattning. Förslag till vidare forskning: Flertalet av våra resultat har inte uppnått statistisk signifikans, vilket troligtvis beror på att vårt urval har varit för litet, vidare forskning borde replikera vår studie på ett större urval. Utöver detta förslag till framtida forskning anser vi att följande bör undersökas:- Hur påverkar färgmärkning uppfattningen om andra GMO-produkter?- Hur blir köpbeteendet påverkat av olika färgnyanser?- Hur förhåller sig varumärke och färg till varandra i köpbeslut? Uppsatsens bidrag: Vår studie har bidragit till att branschen bör tänka på att använda färger med viss försiktighet när det kommer till märkning. Vidare har vi visat att färger påverkar kunders betalningsvilja, vilket är vårt bidrag till ämnet marknadsföring. / Title: A Colorful Consumer Behavior Level: Final assignment for Bachelor Degree in Business Administration Author: Martin Myhrman & Robin Uppman Supervisor: Jonas KågströmDate: 2015 – 05 Aim: The background of our study was grounded in the fact that the research of colors impact are limited in the field of marketing. Studies have also shown that future research should examine which factors that affect consumer’s perception of genetically modified products. The aim of our study is as follows: “The aim of this study is to examine how colored labeling might compensate for the negative perception of genetically modified products.” Method: In this study we have performed an experiment. The experiment took place at a University in Sweden and we had 120 respondent commits. The respondents were asked to perform a taste test in which the color of a label was manipulated between three test groups (red, blue and green). The collected data was analyzed with IBM SPSS Statistics 22, further the results were interpreted and discussed. Result & Conclusions: Our main finding is that the color red on a negative label generated a lower willingness to pay than both blue and green. This result confirms previous research which among other things says that the color red trigger an aggressive mindset and encourage analytical thinking. Furthermore we have seen trends that indicate that colors do not affect the taste and health perception. Suggestions for future research: Many of our results have not been statistically significant, which probably depends on our relatively limited sample, further research should replicate our study with a wider sample. In addition to this suggestion we would like to see further research concerning:- Colors impact on the perception of other GMO products.- The impact of color shades on consumer behavior.- The relation between brands and colors in buying decisions. Contribution of the thesis: Our contribution to people working with marketing is that they should be aware that colored labels may affect the consumer perception. Furthermore we have shown that colors affect consumer’s willingness to pay, which is our contribution to the field of marketing.

Os sistemas de tratamento de esgotos por zona de raízes constituem-se de um leito filtrante plantado com macrófitas emergentes. Tecnologia de baixo custo e, com eficiência comprovada em inúmeros trabalhos, as Estações de Tratamento de Efluentes (ETEs) por zona de raízes apresentam grande potencial para solucionar o problema da inexistência de coleta e tratamento de esgoto em pequenas comunidades. Este trabalho teve por objetivo caracterizar uma ETE por zona de raízes de fluxo vertical com base em variáveis abióticas e microbiológicas. Através da técnica de contagem em placas e da técnica de tubos múltiplos, foi possível estimar a densidade de fungos totais, bactérias heterotróficas, coliformes totais, Escherichia coli, bactérias redutoras de nitrato, bactérias desnitrificantes e bactérias redutoras de sulfato presentes nos diferentes estratos do sistema. Além das análises microbiológicas, foram avaliadas as variáveis abióticas temperatura, pH, oxigênio dissolvido (OD), nitrogênio amoniacal, nitrito, nitrato, nitrogênio total, ortofosfato e Demanda Química de Oxigênio (DQO). As análises foram realizadas em 8 locais, sendo uma referente ao efluente bruto, uma ao efluente tratado, três correspondendo à interface zona de raízes-brita e três ao filtro de areia, num total de 7 amostragens durante um ciclo sazonal. Em 5 amostragens não foi possível observar a redução do NMP de E. coli, apenas na Amostragem 1(C1) e na Amostragem 7 (C7) foi possível observar aproximadamente 66% e 97% de redução, respectivamente. As bactérias desnitrificantes, na maioria dos pontos e as redutoras de sulfato, com exceção da Amostragem 3 (C3), foram determinadas no valor de 1600 NMP.100mL-1. A densidade de bactérias redutoras de nitrato variou, na maioria das amostragens, de 1,8 NMP. 100mL-1 a 19 NMP. 100mL-1. A ETE foi eficiente para a remoção de DQO e fósforo, este último com porcentagem de remoção variando de, aproximadamente, 37% a 69%. A concentração de N-amoniacal foi reduzida em todas as amostragens, com exceção da C3. O pH permaneceu próximo da neutralidade e a concentração de oxigênio dissolvido aumentou na região do filtro de areia. Ao longo do período deste estudo foi observado um baixo desenvolvimento das plantas utilizadas. Com os resultados de quantificação foi possível verificar que a biodegradação é mais intensa nos primeiros 50 cm da ETE. Observou-se redução significativa da densidade de microrganismos no filtro de areia em relação à zona de raízes. Fatores como a idade da estação, que permitiu a formação de um biofilme no filtro de brita, a presença do filtro de areia e a disponibilidade de matéria orgânica podem estar envolvidas com a redução de microrganismos. Em resumo, pode se concluir que a ETE foi eficiente para remoção de microrganismos, porém apenas nos períodos de menor precipitação pluviométrica. / Wastewater root zone treatment systems are constituted of a filter bed planted with emergent macrophytes. A low cost technology with treatment potential proven in numerous studies, the root zone Wastewater Treatment Station (WTS) have great potential to solve the problem of lack of wastewater collection and treatment in small communities. This study aimed to characterize a root zone WTS with vertical flow on the basis of abiotic and microbiological variables. Through the technique of plate count and the multiple tube method was possible to estimate the density of total fungi, heterotrophic bacteria, total coliforms, Escherichia coli, nitrate-reducing bacteria, denitrifying bacteria and sulfate-reducing bacteria in the different strata of the system. In addition to the microbiological analysis the abiotic variables temperature, pH, dissolved oxygen, ammonia nitrogen, nitrite, nitrate, total nitrogen, orthophosphate, Chemical Oxygen Demand (COD) were evaluated. Analyses were performed in eight locations, one related to raw wastewater, one of treated effluent, three corresponding to the root zone interface and three to the sand filter, in a total of seven samples during a seasonal cycle. In 5 samples did not exhibit a reduction in the MPN of E. coli, only in Sample 1 (C1) and Sample 7 (C7) was observed approximately 66% and 97% reduction, respectively. Denitrifying bacteria in most spots and sulfate reducers, with the exception of the Sample 3 (C3) were determined in the amount of 1600 MPN.100mL-1. The density of nitrate-reducing bacteria ranged in most samples, from 1.8 MPN.100mL-1 to 19 MPN.100mL-1. The WTS was efficient for the removal of COD and phosphorus, the latter with removal percentage ranged from approximately 37% to 69 %. The concentration of ammonia-N was reduced in all samples, except for C3. The pH remained near neutrality and the concentration of dissolved oxygen increased in the region of the sand filter. Throughout the study period was observed a less growing of the plants. With the results of quantification it was possible verify that biodegradation is more intense in the first 50 cm of the WTS. It was observed significant reduction in the density of microorganisms in the sand filter compared with the root zone. Factors such as age of the station, which allowed the formation of a biofilm in the filter of gravel, the presence of sand filter and the availability of organic matter may be involved in the reduction of microorganisms. In summary it can be concluded that the WTS was efficient for removal of microorganisms, but only during periods of low rainfall.

Submitted by Mariana Pereira do Rego null (mari_rego@yahoo.com.br) on 2018-01-16T20:18:02Z No. of bitstreams: 1 Dissertacao_Mariana_Pereira_Rego.pdf: 4943487 bytes, checksum: 68ba15599a9a9ea2ef69bfd9006ecf39 (MD5) / Approved for entry into archive by Claudia Adriana Spindola null (claudia@fct.unesp.br) on 2018-01-17T12:39:31Z (GMT) No. of bitstreams: 1 rego_mp_me_prud.pdf: 4943487 bytes, checksum: 68ba15599a9a9ea2ef69bfd9006ecf39 (MD5) / Made available in DSpace on 2018-01-17T12:39:31Z (GMT). No. of bitstreams: 1 rego_mp_me_prud.pdf: 4943487 bytes, checksum: 68ba15599a9a9ea2ef69bfd9006ecf39 (MD5) Previous issue date: 2017-03-02 / A interpretação de um mapa é facilitada com a utilização de textos, os quais facilitam a comunicação do mapa. Os mapas de Sistema de Navegação e Guia de Rota em Automóvel (SINGRA) utilizam textos na área mapeada com a finalidade de auxiliar o motorista na tarefa de navegação. Os nomes de vias são um dos elementos mais importantes no uso como informação de guia de rota. A literatura na área da Cartografia apresenta recomendações para rotular feições cartográficas em mapas estáticos. Porém, os mapas exibidos em SINGRA são dinâmicos e apresentados em um esquema de referência egocêntrica. Então, é questionado se as indicações propostas pela literatura podem ser generalizadas para esse tipo de representação. Este trabalho avalia o tempo de leitura de nomes de vias em mapas de SINGRA, levando-se em consideração diferentes posicionamentos da toponímia de via em mapas com diferentes padrões de malha viária. Para esta avaliação foram projetados 16 mapas, oito com padrão de malha viária regular e oito com padrão de malha viária irregular. Um conjunto apresentou nomes de vias com posicionamento alinhado horizontalmente e outro com os nomes seguindo a via. A concepção dos mapas foi baseada em princípios de agrupamento perceptível, segregação de figura-fundo, bem como em técnicas de tipografia, uso de tipos na cartografia e, também, na análise de mapas de sistemas de navegação de ampla utilização no mercado. A avaliação foi realizada com 20 motoristas novos. O experimento ocorreu dentro de um automóvel estacionado. A tarefa do participante foi buscar um nome de via no mapa exibido em uma tela de pequenas dimensões, bem como falar em voz alta o nome da via solicitada pelo pesquisador. A duração do tempo de leitura foi extraída e analisada. Em mapa com padrão de malha viária regular, a análise estatística mostrou que não houve diferença significativa no tempo de leitura entre os diferentes posicionamentos do texto, tanto para o nome da via em que se encontra quanto para o nome da via em que irá entrar. Por outro lado, em mapa com padrão de malha viária irregular e nome com o posicionamento alinhado horizontalmente, a análise estatística dos dados revelou que o tempo de leitura do nome da via em que o motorista irá entrar é significativamente mais rápido do que a leitura do nome da via em que se encontra. Maiores implicações são apresentadas e discutidas. / Reading a map is facilitated by using texts, which facilitate the communication of the map. InCar Route Guidance and Navigation System maps (RGNS) use texts in the map to assist drivers in the navigation task. Road names are one of the most important elements in the use as route guidance information. The literature in the Cartography field presents recommendations for labeling cartographic features in static maps. However, maps showed in RGNS are dynamic and presented in an egocentric reference. Thus, it is questioned whether those results can be generalized to this kind of representation. This work evaluates the time in which drivers start reading road names in maps of RGNS, taking into account different positions for the road toponymy in maps with different road network patterns. For this evaluation, 16 maps were designed; eight with road pattern similar to a regular-grid network and eight with road pattern similar to an irregular-grid network. Half of the maps were designed with names aligned horizontally and the other half with names following the road. Creating maps was based on principles of perceptual grouping, figure-ground segregation, as well techniques of typography, use of types in Cartography and, also, in the analysis of some maps of navigation systems with high acceptance in the market. The evaluation was performed with 20 drivers aged between 20 and 30 years. The experiment took place inside a car parked. The task of the participant was looking for a street name showed in a small screen and speech in a loud voice the name requested by the researcher. The time took to start reading was gathered an analyzed. For maps with road pattern similar to a regular-grid network the analysis showed no significant difference in the time in which drivers start reading road names among different text positioning, both for road name where they are located and for road name where they will turn. On the other hands, for maps with road pattern similar to an irregular road network and name aligned horizontally, the statistical analysis revealed the reading time for the name in which drivers will turn is significantly faster than reading time for the name in which drivers are located. More implications are presented and discussed.

Cette étude se propose d'analyser les développements qui ont mené à l'état actuel du champ journalistique roumain, après la crise financière de 2008, par lesquels ce milieu professionnel ne parvient pas à convaincre ses acteurs de la viabilité de ses principes. Ma principale hypothèse est que la collision entre deux systèmes de valeurs divergents –l'intersection du modèle allogène, néolibéral, avec les valeurs et les nécessités locales –établit un champ hybride intégrant des éléments des deux cultures, sans incorporer la somme de leurs éléments. Ce champ hybride, caractérisé par un haut degré d'ouverture envers la renégociation, la réinterprétation et le rétablissement des principes qui guident le journalisme, engendre aussi une certaine dimension anomique au sein de ses acteurs. Afin d’établir l’existence du champ journalistique en Roumanie après 2008, une analyse à partir de trois dimensions principales était envisagée : une première dimension serait la rupture politique, qui a imposé une réflexion sur les directions et les choix des modèles dans le nouveau marché médiatique pluraliste ; une deuxième dimension identifiée est le profond changement technologique superposé sur cette étape de compréhension de l’agir journalistique ; troisièmement, la crise financière débutée en 2008, qui a déstabilisé mondialement le milieu journalistique et qui a engendré une remise en cause du journalisme. Nous avons pu remarquer : • Une contradiction idéologique au niveau macro, c'est à dire que les institutions adhèrent au modèle, mais ce n'est pas le principe directeur de leurs démarches, qui sont surtout guidées par les réalités en place ; • Et au niveau micro, une contradiction marquante entre la compréhension du modèle et la manière d’agir : décalage entre le niveau argumentatif – avec la compréhension que le modèle de l'Ouest qui est fortement attractif – et le mode d'agir, où les individus doivent se plier aux coutumes et aux valeurs locales, qui ne sont pas en concordance avec le système de référence auquel ils adhéreraient. / This study aims to analyze the developments that led to the current state of the Romanianjournalistic field, after the financial crisis of 2008, by which this professional environment fails to convince its actors of the viability of its principles. My main hypothesis is that the collision between two divergent value systems -­ the intersection of the neoliberal allogeneic model with local values and necessities -­ establishes a hybrid field integrating elements of both cultures without incorporating the sum of their elements. This hybrid field, characterized by a high degree of openness towards renegotiation, reinterpretation and restoration of the principles that guide journalism, also creates a certain anomic dimension of its actors. In order to establish the existence of the journalistic field in Romania after 2008, an analysis based on three main dimensions was envisaged: a first dimension would be the political rupture which imposed a reflection on the directions and choices of models in the new pluralist media market;; a second dimension identified is the profound technological change superimposed on this stage of understanding journalistic acts;; third, the financial crisis which began in 2008, which destabilized the journalistic environment in Romania. Our main discovery is that of the existence of double standards in the practice and in the evaluation of Romanian journalism by its actors:• An ideological contradiction at the macro level, i.e. institutions adhere to the model, but this is not the guiding principle of their approaches, which are mainly guided by the realities in place ;• At the micro level, the contradiction between the understanding of the model and the waythis model is enacted: a discrepancy between the argumentative level -­ with theunderstanding that the Western model is highly attractive -­ and the mode of action whereindividuals must comply with local customs and values, which are not in accordance with thesystem of reference to which they adhere.

Gotlandssnus AB är en industriell organisation som producerar tobaksprodukten snus och det nikotinfria alternativet Qvitt. Företaget har sedan starten 2004 haft en snabb tillväxt och det övergripande kvalitetsarbetet har blivit lidande. Delprocessen utleveranser bedömdes efter genomförd förstudie vara i behov av förbättring då medarbetarna upplevde att processen innehöll onödiga och tidskrävande moment. Syftet med studien var att ta fram ett förbättringsförslag för verkligt test inklusive implementeringsplan för delprocessen utleveranser. Frågeställningar som använts i studien är (1) Hur kan processen för utleveranser förbättras? (2) Leder föreslagna åtgärder till en förbättring? (3) Kan värderingar, arbetssätt och verktyg från offensiv kvalitetsutveckling tillämpas i förbättringsarbetet av processen för utleveranser? Den teoretiska bakgrunden visar att offensiv kvalitetsutveckling kan beskrivas som en kombination av värderingar, arbetssätt och verktyg som samverkar för att aktivt förebygga kvalitetsbrister och främja arbetet med ständig förbättring istället för att kontrollera och reparera uppkomna brister. Arbetssättet DMAIC har legat till grund för föbättringsarbetet där fokusgruppsmöten, semistrukturerade intervjuer, observationer har använts för att samla in kvalitativa data. För insamling av kvantitativa data har orderhistorik inhämtats och en tidsstudie har genomförts för att kunna basera beslut på fakta. Insamlad data har analyserats genom kvalitetstekniska verktyg. Resultatet visar att (1) Det upplevda problemt med delprocessen var ineffektiva moment där momentet etikettering visade sig vara mest tidskrävande samt ansågs vara dubbelarbete. I delprocessen produktion fanns redan ett etiketteringsmoment som var möjligt att förändra och därmed flytta momentet från delprocessen utleveranser. (2) Förbättringen resulterade i en ökad effektivitet i delprocessen utleveranser utan att påverka effektiviteten i delprocessen produktion. (3) Arbetsättet DMAIC har skapat en systematisk arbetsgång i förbättringsarbetet med hjälp av värderingar som varit vägledande. Verktyg har skapat förutsättningar för definiering av problem, mätning, analys och förbättring. / Gotlandssnus AB is an industrial organization that produces tobacco product snus and the nicotine-free option Qvitt. The company has experienced rapid growth since 2004 and qualitywork has been affected. After completion of a preliminary study, the subprocess deliveries was considered to be in need of improvement. The employees felt that the process consisted of unnecessary and time-consuming moments. The purpose of the study was to develop an improvement proposal for test including an implementation plan for the subprocess deliveries. Questions used in the study was (1) How can the subprocess delivery be improved? (2) Are proposed actions lead to improvment? (3) Can values, practices and tools from offensive quality development be applied in the improvement work of the subprocess deliveries? The theoretical background shows that offensive quality development can be described as a combination of values, practices and tools that work together to actively prevent quality shortages and promote continuous improvement efforts, instead of controlling and repairing. The DMAIC approach has provided the basis for the improvement work, where focus group meetings, semistructured interviews and observations have been used to collect qualitative data. For the collection of quantitative data, order history has been obtained and a time study has been conducted to base decisions on facts. The collected data has been analyzed using quality tools. The result shows that (1) The perceived problem with the subprocess was ineffective moments where the moment of labeling proved to be most time consuming and was considered duplication. In the subprocess production there was already a labeling moment that was possible to change. The moment could therefore be moved from subprocess deliveries to subprocess production. (2) The improvement resulted in increased efficiency in the subprocess deliveries without affecting the efficiency in the subprocess production. (3) The practic method DMAIC has created a systematic workflow in the improvement work using values that have been guiding. Tools have created the conditions for defining problems, measurement, analysis and improvement.

Le cadmium (Cd) est un élément toxique. Les activités humaines ont contaminé un large éventail de sols agricoles. L'exposition de l'homme au Cd se fait majoritairement par voie alimentaire, notamment à travers les aliments de base tels que les céréales. Le blé dur accumule naturellement plus de Cd dans ses grains que les autres céréales. Une fraction significative de la production française de blé dur dépasse la limite réglementaire européenne fixée pour le Cd. Il est donc nécessaire de réduire l'accumulation de Cd dans les grains de blé dur. Cette thèse portant sur l'écophysiologie de l'allocation du Cd aux grains chez le blé dur a pour ambition d'aider au développement de stratégies agronomiques visant à réduire le niveau de contamination en Cd du blé dur et de ses dérivés.Dans un premier temps, nous avons étudié la relation entre la structure de la biomasse aérienne et l'allocation de Cd aux grains. Nous avons fait l'hypothèse que la répartition de la biomasse aérienne entre pailles et grains était un facteur déterminant de l'allocation du Cd aux grains. Huit cultivars Français de blé dur - de hauteur de paille contrastée - ont été cultivés en présence de Cd. Comme prévu, le principal facteur expliquant la différence d'accumulation de Cd dans le grain était la structure de la biomasse aérienne. Les cultivars allouant une plus grande proportion de leur biomasse aérienne aux pailles - autrement dit les cultivars à longue tige - avaient tendance à accumuler moins de Cd dans leurs grains, car les tiges et les feuilles sont des puits de Cd en concurrence avec les grains lors de leur remplissage.Les minéraux importés dans les grains proviennent soit de leur absorption directe par la racine après l'anthèse, soit de leur remobilisation depuis des réserves constituées avant l'anthèse. La deuxième partie de ce travail a été consacrée à déterminer l'importance quantitative de ces deux « sources » pour le Cd chez le blé dur, et de préciser comment leur contribution relative varie entre cultivars et avec le niveau d'azote (N). Le traçage isotopique a été utilisé pour suivre le flux de Cd absorbé après l'anthèse. L'impact du niveau d'azote a été testé en privant la moitié des plantes de N après l'anthèse, sur deux cultivars montrant une capacité contrastée à accumuler le Cd dans leurs grains. La contribution de la remobilisation a été estimé à 50%, ce qui signifie que la moitié du Cd accumulé dans les grains provenait du Cd prélevé après l'anthèse. Le Cd a été remobilisé à partir des tiges, peut-être des racines, mais pas à partir des feuilles. La contribution de la remobilisation n'a pas varié entre les deux cultivars, de sorte qu'aucune relation entre la « source » de Cd et son niveau d'accumulation dans le grain n'a été mise en évidence. La privation d'azote en phase de remplissage a stimulé la remobilisation de N sans affecter celle de Cd, ce qui suggère que la remobilisation de Cd est un processus indépendant de la sénescence.En troisième lieu, nous avons examiné comment les caractéristiques d'allocation de Cd aux grains étaient modulées par le niveau d'exposition au Cd. [...]Enfin, nous nous sommes intéressés à la localisation de Cd dans le grain. [...] Ce travail a fourni la première carte de localisation de Cd dans un grain de blé dur. La distribution de Cd s'est caractérisée par une forte accumulation de Cd dans le sillon et par une dissémination dans l'endosperme amylacé plus prononcée que celle de Fe et Zn. / Cadmium (Cd) is a toxic element. Human activities have contaminated a wide range of agricultural soils. Most of Cd entering human bodies is through the dietary intake, and especially through staple food like cereals. Durum wheat naturally accumulates more Cd in its grains than other cereals. A significant fraction of the French durum wheat production has been found to exceed the European regulatory limit set for Cd. There is thus a need to reduce the accumulation of Cd in durum wheat grains. This thesis is dedicated to a better understanding of the ecophysiology of Cd allocation to the grains in durum wheat, with the ambition of helping to find agronomic strategies to reduce the Cd contamination level of durum wheat products.In first, we investigated the relationship between the aboveground partitioning of Cd and the shoot allometry. We hypothesized that the partitioning of shoot biomass between grains and straws is a driver of the allocation of Cd to the grains. Eight French durum wheat cultivars differing in their stem height were grown in presence of Cd. As expected, the main factor explaining the difference in their grain Cd was the shoot biomass partitioning. Cultivars allocating a higher proportion of their aerial biomass to the straws, i.e. long-stem cultivars, tended to accumulate less Cd in their grains because stems and leaves are sinks for Cd in competition with developing grains.Minerals imported into cereal grains originate from either direct post-anthesis root uptake or from the remobilization of pre-anthesis stores. The second part of this work was dedicated to determine the quantitative importance of these two pathways for Cd in durum wheat, and how their relative contribution vary between cultivars and with the level of nitrogen (N) supply. Stable isotopic labelling was used to trace the flux of Cd taken up post-anthesis. The impact of N supply was tested by depriving half of the plants of N after anthesis, in two cultivars showing a contrasted ability to accumulate Cd in their grains. The contribution of Cd remobilization was around 50%, which means that half of Cd in grains originated from Cd taken up pre-anthesis. Cd was remobilized from stems, possibly from roots, but not from leaves. The contribution of remobilization did not vary between the two cultivars so that no relationship between the pathway and the level of accumulation of Cd in grain was evidenced. Post-anthesis N deprivation triggered the remobilization of N without affecting that of Cd, which suggests that Cd remobilization is a senescent-independent process.In third, we investigated how the characteristics of Cd allocation to the grains was affected by the level of Cd exposure. [...]In last, we focused on how Cd was distributed within durum wheat grains. [...] This work provided the first map of Cd localization in durum wheat grains. Cd distribution was characterized by a strong accumulation of Cd in the crease and by a non-negligible dissemination in the starchy endosperm, as compared to Fe and Zn.

Les objectifs de cette thèse étaient (i) d'étudier les mécanismes par lesquels les nématodes bactérivores régulent les flux de nutriments (N et P) dans la rhizosphère du riz pluvial dans un sol ferrallitique de Madagascar, (ii) d'étudier les effets des interactions bactéries – bactérivores sur les fonctions de la plante (croissance et nutrition), et (iii) d'évaluer les principaux facteurs contrôlant la boucle microbienne des sols dans une optique d'intensification. Notre modèle biologique comprenait Acrobeloides sp. (Cephalobidae) et Oryza sativa (Poaceae).Deux voies ont été proposées pour expliquer les effets positifs des bactérivores sur la disponibilité des nutriments et les fonctions de la plante: voie de minéralisation et voie d'exploration. Afin d'identifier l'implication de chaque voie dans les flux de P inorganique à l'interface sol-plante nous avons utilisé le radio-isotope 32P comme traceur. Lorsque le pH du sol est corrigé par l'ajout de dolomie, la présence des nématodes bactérivores améliore la minéralisation nette de P, la production de biomasse et la nutrition de la plante sans modifier la ramification du système racinaire, contrairement à ce qui a été observé par certains auteurs en présence de protistes. En effet, en présence de nématodes et de dolomie, la L-value dans les parties aériennes de la plante augmente de 49%, la biomasse totale de la plante augmente de 22%, et la quantité de P total dans les tissus de la plante augmente de 9%. Ainsi, Acrobeloides sp. stimule le prélèvement de P par la plante via la voie nutritionnelle ou voie de minéralisation.Les effets de Acrobeloides sp. sur les fonctions de la plante sont variables (positives, neutres, négatives), en fonction des pratiques agricoles et des caractéristiques abiotiques du sol. Tout d'abord, ces effets peuvent dépendre de la variété de riz puisque l'attractivité des nématodes Acrobeloides sp. par la rhizosphère du riz varie en fonction des variétés de riz pluvial, plus précisément en fonction de la composition et de la quantité d'exsudats racinaires libérés par la plante. Ensuite, l'activité mutualiste des nématodes est influencée (maximisée) par la présence d'arbres (agroforesterie) dans la parcelle de riz pluvial. En plus des plantes, les paramètres édaphiques étaient des facteurs clés. L'activité mutualiste des nématodes est fortement limitée par le pouvoir fixateur des Ferralsols. Ainsi, l'ajout de dolomie limite la capacité de sorption de P du sol et améliore l'activité mutualiste des nématodes bactérivores. Enfin, l'activité mutualiste des nématodes sur la croissance et la nutrition du riz pluvial est favorisée par les valeurs élevées de pH et de teneur en Mg dans le sol. Pour conclure nous avons trouvé qu'il est possible d'intensifier l'activité mutualiste des nématodes bactérivores dans un sol tropical pauvre à travers des pratiques agricoles spécifiques (gestion des sols, agroforesterie). / Using Acrobeloides sp. (Cephalobidae) and Oryza sativa (Poaceae), we aimed at (i) studying the effects of bacterivorous nematodes on plant functions growing in a nutrient-poor soil in Madagascar, (ii) testing the mechanisms involved in the mutualistic activity of the bacterivorous nematodes in a strong P-depleted Ferralsol from the highlands of Madagascar, and (iii) identifying the agronomic and edaphic factors that can drive the soil microbial loop.Two pathways have been proposed to explain the positive effects of bacterial-feeders on nutrients availability and plant functions: mineralization pathway and exploration pathway. In order to test the involvement of each pathway in the mutualistic activity of bacterivorous nematodes, we assessed the effect of nematodes inoculation on inorganic P flows from soil to plant using the 32P labelling technique. When the soil pH was corrected with dolomite lime, we showed that the presence of Acrobeloides sp. improved net P mineralization and plant (Oryza sativa) functions (growth and nutrition) but did not alter lateral root growth as protists do. Indeed, in the presence of nematodes and dolomite, the shoot L-value increased by 49%, the plant total biomass increased by 22% and the plant total P amount increased by 9%. Thus, Acrobeloides sp. increased plant P uptake through the "nutritional" or "mineralization" pathway.The effects of Acrobeloides sp. on Oryza sativa functions were variable (positive, neutral or negative) according to agricultural practices and soil abiotic variables. First, these effects may depend on the rice cultivar used in the experiment. Indeed, the nematodes attractancy to root-adhering soils varied according to upland rice cultivar, probably according to the amount and composition of root exudates. The mutualistic activity of nematodes is also influenced (maximized) by the presence of trees (agroforestry) in the rice field. Besides plants, the abiotic soil parameters were key drivers. The mutualistic activity of nematodes was strongly limited by the ability of Ferralsols to precipitate and chemisorb phosphates. The addition of dolomite lime limited phosphates sorption on soil and enhanced the mutualistic activity of the nematodes. Also, the high values of soil pH and Mg content tended to increase the mutualistic activity of the bacterivorous nematodes on rice growth and nutrition. To conclude, we found that it is possible to drive the mutualistic activity of bacterivorous nematodes in poor tropical soils through specific soil and agricultural practices.

Les glycosaminoglycanes (GAG) forment une famille de polysaccharides linéaires retrouvés dans tous les tissus, au niveau des matrices extracellulaires et des surfaces cellulaires. Les héparanes sulfates (HS) sont des membres importants de cette famille et sont liés à une protéine dite cœur pour former ensemble le protéoglycane (PG). Selon le tissu et la nature de la protéine cœur, les HS, composés d'unités disaccharidiques de N-acétylglucosamine (GlcNAc) et d'acide glucuronique (GlcA) [-4GlcAβ1-4GlcNAcα1-] vont subir de nombreuses modifications. En effet, les HS sont modifiés par différentes sulfatations au niveau des deux oses et une épimérisation de l'acide glucuronique en acide iduronique (IdoA). Les différentes structures saccharidiques élaborées vont pouvoir être alors interagir avec une très grande quantité de protéines et jouer des rôles divers dans l'inflammation, la prolifération cellulaire, l'angiogenèse, la réponse immunitaire, l'attachement viral…L'étude de la structure des HS, du fait de la nature flexible et hétérogène de ces molécules, a été principalement focalisée sur des analyses fragmentaires du polysaccharide au niveau des séquences d'interaction avec les protéines. Lors de ces dépolymérisations, des informations sur le polysaccharide, notamment l'épimérisation, sont perdues.Dans ce travail, nous avons développé une approche basée sur la résonance magnétique nucléaire (RMN) bidimensionnelle 1H-13C pour l'étude de la composition saccharidique des HS réalisée directement à partir des HS isolés de cellules marquées au 13C. Pour cela, un protocole efficace de marquage et de purification des polysaccharides a été mis en place. En intégrant le volume des pics à différents déplacements chimiques par RMN, cette analyse non-destructive permet de déterminer à la fois le profil de sulfatation et d'épimérisation des HS. Cette analyse est appliquée efficacement à différents types cellulaires et est de grand intérêt pour mieux comprendre les changements dans les structures d'HS qui ont lieu lors de régulations physiologiques ou lors de développement pathologiques.Ces résultats ont permis d'ouvrir la voie à l'analyse des HS directement au niveau des cellules par RMN du solide. Les études dans ce contexte représentent un enjeu majeur pour la compréhension des différents rôles des HS et leur capacité à interagir avec une myriade de protéines in vivo. / Glycosaminoglycans (GAGs) belong to a linear polysaccharide family which are found within all tissues, at the extracellular matrix and cell surfaces levels. Heparan Sulfates (HS) are one of the major members of this family, they are bound to a core protein to form altogether the so-called proteoglycan (PG). Depending on the localization and on the core protein, the HS – composed of a N-acetylglucosamine (GlcNAc) and a glucuronic acid (GlcA) [-4GlcAβ1-4GlcNAcα1-] building block – undergo various modifications. Indeed, HS can be sulfated at different positions on both monosaccharide and the GlcA can be epimerized into an iduronic acid (IdoA). The fine structures of the polysaccharide will be able to interact with a large range of proteins and play a plethora of roles such as in inflammation processes, cell proliferation, angiogenesis, immune responses, viral attachment…The HS structural studies, due to the flexibility and heterogeneity of the polysaccharide, have so far been restricted to HS fragments able to bind proteins. The depolymerization techniques induce valuable information losses such as epimerization.In this work, we have successfully developed a nuclear magnetic resonance (NMR)-based approach to study HS features from 13C metabolically enriched cells. For this, an effective protocol to label and purify HS has been set up. By integrating peaks' volumes at well-resolved 1H-13C chemical shifts by NMR, the sulfation, epimerization and disaccharide profile can be determined from full-length HS. This method has been used to study HS from various cell types and is of important interest to better understand changes in HS structures that occur through physiologic and pathologic events.The results obtained open the way to analyze HS directly at the cell surface via solid state NMR techniques. In this context, these studies are a major challenge to decipher the different roles of HS and their ability to interact with so many partners in vivo.