Made available in DSpace on 2014-06-11T19:33:01Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-02-10Bitstream added on 2014-06-13T20:44:33Z : No. of bitstreams: 1 murata_ss_dr_araca.pdf: 3025122 bytes, checksum: d6ebabe611a7dce5412ed2e2cf0535db (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A dentição decídua é passível de ser acometida por traumatismos, lesões cariosas precoces (cárie de mamadeira) ou outro tipo de injúria, que podem comprometer a vitalidade pulpar desses dentes, inclusive com rizogênese incompleta. A escassez de trabalho específico sobre o assunto, bem como a importância de solucionar adequadamente esse tipo de problema, em dentes decíduos com rizogênese incompleta, estimulam a realização de investigações sobre o assunto. Portanto, o objetivo deste estudo foi avaliar, histologicamente, a resposta dos tecidos apicais e periapicais de dentes decíduos de cães, com rizogênese incompleta, após biopulpectomia e obturação dos canais radiculares com hidróxido de cálcio em diferentes veículos. Assim, os canais radiculares de 80 dentes decíduos anteriores de 6 cães da mesma ninhada, com 50 dias de idade, e com rizogênese incompleta, foram empregados neste estudo. Após o preparo biomecânico, os canais radiculares foram obturados com os seguintes materiais: Grupo 1- pasta Vitapex (hidróxido de cálcio, iodofórmio e óleo de silicone), Grupo 2- hidróxido de cálcio acrescido de iodofórmio e soro fisiológico, Grupo 3- hidróxido de cálcio associado ao Lipiodol e, Grupo 4 - controle - dentes com canais preparados e não obturados. Trinta dias após o tratamento, os animais foram mortos e os espécimes preparados para análise histomorfológica. A análise estatística dos resultados permitiu que os materiais estudados fossem ordenados do melhor para o pior resultado da seguinte forma: a) hidróxido de cálcio acrescido de iodofórmio e soro fisiológico, b) pasta Vitapex (hidróxido de cálcio acrescido de iodofórmio e óleo de silicone), c) hidróxido de cálcio associado ao lipiodol, d) controle. / The deciduous teeth with open apex are susceptible to be traumatized by carious lesions or other offence type that can engage the pulp vitality of those teeth. The lacking of specific work on the subject, as well as the importance of solving this kind of problem appropriately stimulates the accomplishment of investigations on the subject. Therefore, the subject of this study was to evaluate, histologically, the behavior of apical tissues of deciduous dogs teeth with open apex, after biopulpectomy and root canal filling with calcium hydroxide in different vehicles. The root canals of 80 deciduous teeth, from 6 dogs of the same hatch, with 50 days of age, and with open apex, were used in this study. After the biomechanical preparation, the root canals were filled with the following materials: Vitapex - calcium hydroxide added to iodoform and silicon oil; paste of calcium hydroxide with iodoform and saline; paste of calcium hydroxide with lipiodol, and as control group, teeth with root canal prepared but not filled. Thirty days after the treatment, the animals were killed and the specimens were prepared for histomorphological analysis. The statistical analysis of the results allowed the studied materials to be ordered from the best to the worst in the following way: a) calcium hydroxide added to iodoform and saline, b) Vitapex - calcium hydroxide added to iodoform and silicon oil, c) calcium hydroxide added to Lipiodol, d) control. It was observed statistical significant difference (p=0.05) among the results of the groups of calcium hydroxide associated to iodoform and saline with the calcium hydroxide group associated to lipiodol, as well as the 3 groups filled with calcium hydroxide pastes with the control group (p=0.001). It was concluded that the 3 pastes of calcium hydroxide studied can be used as root canal filling material in the treatment of deciduous teeth with open apex.

Predadores de topo desempenham um papel importante na manutenção dos sistemas em que eles ocorrem porque influenciam diretamente a estrutura e a dinâmica de comunidades. Desta forma, este estudo descreveu alguns mecanismos de co-ocorrência espaço-temporal entre a onça-pintada (Panthera onca) e duas espécies de mesopredadores (Puma concolor e Leopardus pardalis), o seu controle top-down na comunidade de mamíferos e os requerimentos ambientais que determinam a sua distribuição no bioma Amazônia. Para as análises de co-ocorrência espaço-temporal foram utilizados o modelo de ocupação e a densidade de Kernel utilizando os registros de armadilhamento fotográfico (2008-2011). Para descrever o controle top-down foi elaborada uma rede trófica utilizando os itens alimentares consumidos pelas espécies e disponíveis na literatura (1983-2014). Para indicar quais as áreas mais adequadas foi utilizado o modelo de distribuição de espécies utilizando as localizações geográficas de ocorrência da espécie que foram compiladas de três diferentes bases de dados (2000-2013). A ocorrência das duas espécies de mesopredadores não foi diferente nos sítios com e sem a onça-pintada nas quatro temporadas de amostragem. A probabilidade de detecção da jaguatirica foi maior nos sítios com a presença da onça-pintada em apenas uma temporada de amostragem. A sobreposição no período de atividade das espécies de mesopredadores com a onça-pintada foi baixa, com cerca de 55% de sobreposição. Também ocorreu uma mudança razoável no período de atividade das espécies entre as temporadas de amostragem, com mínima de 32% e máxima de 56% de sobreposição. As maiores diferenças na detecção e na sobreposição temporal ocorreram na terceira temporada quando teve o maior número de capturas e recapturas da onça-pintada. A rede trófica apresentou seis níveis e grande riqueza de espécies e densidade de interações. Após a remoção da onça-pintada, houve a perda de um nível trófico e de aproximadamente 20% de interações. Quando comparada a distribuição atual da onça-pintada com a histórica, foi possível constatar a perda de espaço ambiental em áreas mais frias (< 6,3 °C), mais secas (< 288 mm), mais úmidas (> 7517 mm) e com maior elevação (> 3597 m). O modelo de distribuição também indicou que muitas áreas potenciais estão disponíveis à ocorrência da onça-pintada e que algumas merecem atenção, especialmente, nas porções leste e sul da Amazônia onde a espécie corre maior risco de desaparecimento local devido à antropização acelerada. Este estudo forneceu significativa contribuição para a compreensão da população de onça-pintada na Amazônia, bioma que ainda possui a maior lacuna de conhecimento sobre a biologia e ecologia da espécie. Demonstrou o efeito da sua presença na detectabilidade e no período de atividade de outras espécies. Também demonstrou seu papel ecológico como predador de topo exclusivo porque foi a única espécie que predou todas as outras de níveis tróficos inferiores. Descreveu o espaço ambiental originalmente ocupado (distribuição histórica) e o perdido (distribuição atual). Indicou as áreas mais adequadas à sua ocorrência e aquelas potenciais ao seu desaparecimento. / Apex predators play an important role in the maintenance of systems in which occur because they directly influence the structure and dynamics of communities Thus, this thesis aims to describe some of the mechanisms of spatio-temporal co-occurrence between the jaguar (Panthera onca) and mesopredators (Puma concolor and Leopardus pardalis), their top-down control on the community and environmental requirements that determine their distribution. To the analyses of spatio-temporal co-occurrence were used the occupancy model and the Kernel density with records derived from camera trapping (2008-2011). To the analysis of trophic networks was used a foodweb model with prey spectra of felids compiled from the available literature (1983-2014). To indicate the most suitable areas to its occurrence was used a species distribution model with geographic location of the species compiled from three different databases. The occupation of the two species of mesopredators was not different among sites with and without jaguar. The probability of detection was different for ocelot, with higher detection on sites with than without jaguar. The overlap in the activity pattern among jaguar and mesopredators was low, with approximately 55% of overlapping. Also there was a reasonable change in the overlap between sampling seasons, with a minimum of 32% and maximum of 56% of the difference in the activity pattern. The differences in the detection and temporal overlap occurred in the third season when occurred the highest number of jaguar captures and recaptures. The trophic network presented six levels and, a high species richness and links density. After removal of the jaguar, a trophic level and approximately 20% of links were lost. When compared historical and current distributions, the loss of environmental space occurred in areas colder (< 6.3 ° C), drier (< 288 mm), wetter (> 7517 mm) and at higher elevation (> 3597 m). The distribution model also indicated that there is many potential suitable areas available to the jaguar occurrence and, some of them deserve attention, particularly, in eastern and southern portions of Amazonia where the species is most at risk of local extinction. This study provided a significant contribution to the knowledge of the population of jaguar in the Amazon biome which still has the largest gap of information on the biology and ecology of the species. It demonstrated the effect of the presence of the species in the detectability and the activity pattern of others. Also, it demonstrated their ecological role as an apex predator exclusive because it was the only one that ate all other species of lower trophic levels. It described the environmental space originally occupied (historical distribution) and lost (current distribution). It indicated potential suitable areas to its occurrence and threatened areas to its disappearance.

Development of selected invasive species and meadow vegetation classification algorithm in the Krkonoše Mountains using hyperspectral data Abstract The thesis deals with utilization of airbone APEX hyperspectral image data for selected invasive species and meadow vegetation classification in the study area of the Krkonoše Mountains National Park. The mian goal of the thesis was to develop of classification algorithm based on proposed vegetation indices. The approach was based on the utilization of in-situ LAI, fAPAR, chlorophyll content data and analysis of their relation with vegetation spectral properties. The work also deals with several problems regarding LAI - vegetation indices relationship, namely saturation of LAI and mutual correlation of LAI and chlorophyll content. Tha classification was focued on invasive species Rumex alpinus and Lupinus polyphyllus, meadow vegetation with dominant Nardus stricta and dominant Trisetum flavescens and cutted lawns. Besides the proposed approach, the presented work resulted in several classification maps of study area and in spectral libraries, containing ground level spectra of studied invasive species, meadow vegetation types and several other meadow species. Keywords: hyperspectral image data, APEX, LAI, fAPAR, vegetation indices, invasive species, meadow...

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Die vorliegende Arbeit beschreibt die Herstellung und Charakterisierung der ersten Antikörper gegen Triacetontriperoxid (TATP), einem hoch empfindlichen und unkonventionellen (nicht-kommerziellen) Initialsprengstoff. Entscheidend dafür war die Synthese eines TATP-imitierenden Haptens, welches die typische nonagonale Struktur des TATP mit seinen drei Peroxid- und sechs Methylgruppen nahezu perfekt nachbildet, aber den Vorzug einer zusätzlichen Carboxygruppe zur kovalenten Kopplung an Proteine aufweist. Dadurch konnte das TATP-Hapten an Rinderserumalbumin (BSA) gebunden werden, um ein immunogenes Konjugat zu erzeugen, welches die erfolgreiche Immunisierung zweier Säugetierarten, Maus und Kaninchen, ermöglichte. Der Verlauf der In vivo-Immunisierungen wurde durch die Analyse der Tierseren in regelmäßigen Abständen mittels enzymgekoppeltem Immunoassay (ELISA) verfolgt. Die polyklonalen Antikörper beider Spezies waren ungewöhnlich selektiv gegenüber TATP. Jedoch unterschied sich die Affinität der Antikörper der zwei Spezies um das 5000-fache, wobei die Kaninchenseren den Mausseren überlegen waren. Entsprechend war auch die mit Kaninchenserum erreichbare TATP-Nachweisgrenze von 0.01 µg/L deutlich besser im Vergleich zu 50 µg/L, die mit Mausserum erzielt wurden. Der Messbereich des TATP-ELISA mit Kaninchenserum deckte zudem mehr als vier Zehnerpotenzen ab, wie mittels Präzisionsprofil bestimmt wurde. Die erhaltenen TATP-Antikörper aus Kaninchen stehen damit Anwendungen in Nachweissystemen für die sehr empfindliche Detektion von TATP zur Verfügung, die u. a. in sicherheitsrelevanten Bereichen zum Einsatz kommen könnten. Als erste Anwendung wurde ein TATP-ELISA realisiert, der im Rahmen dieser Arbeit ausführlich optimiert wurde. Außerdem wurden erste Schritte zur Entwicklung eines TATP-Schnelltests (LFA) unternommen. Weitere Biosensoren auf Grundlage der neu entwickelten TATP-Antikörper sind denkbar. / The present work decribes the production and characterization of the first antibodies against triacetone triperoxide (TATP), a highly sensitive and improvised (non-commercial) primary explosive. Crucial to this work was the synthesis of a TATP-related hapten that mimics almost perfectly the typical nonagonal structure of TATP with its three peroxide and six methyl groups. Advantageously, it has an additional carboxylic acid group, which provides a conjugation site for covalent attachment to proteins. Thus, the TATP hapten could be linked to bovine serum albumin (BSA) to produce an immunogenic conjugate, allowing the successful immunization of two different mammalian species, mouse and rabbit. The in vivo immunization progress was followed by periodically analyzing the animals’ sera using enzyme-linked immunosorbent assay (ELISA). The polyclonal antibodies of both species were remarkably selective to TATP. The affinity of these TATP-antibodies was, however, different between the two species, with the rabbit sera showing an affinity about 5000-fold superior than the murine one. Consequently, the TATP detection limit of 0.01 µg/L was considerably better using the sera from rabbit in contrast to 50 µg/L when mouse serum was used. The working range of the TATP-ELISA with rabbit sera covers more than four decades, calculated from a precision profile. The obtained TATP antibodies from rabbit are now available for applications in highly sensitive detection systems for TATP, which could be employed, among others, in security-relevant areas. The first application was the realization of a TATP-ELISA, which was extensively optimized within the course of this work. Furthermore, the first steps towards the development of a lateral flow assay (LFA) targeting TATP were taken, making conceivable further biosensor platforms based on the newly developed TATP antibodies.

Made available in DSpace on 2014-07-29T15:21:58Z (GMT). No. of bitstreams: 1 Dissertacao Andre Luiz Gomide de Morais.pdf: 1627953 bytes, checksum: 05ab427707618c3afdeb890e320268e6 (MD5) Previous issue date: 2012-02-13 / Introduction Strategies to obtain the working length to prepare and fill the root canals has been relevant theme of discussion in endodontics. The purpose of this study was to compare in vivo the canal root working length measures determined by cone beam computed tomography (CBCT) images with the ones obtained by using periapical radiograph and electronic apex locator. Methods The root canal working lengths of 30 single-rooted teeth from 19 patients whose diagnosis was apical periodontitis were evaluated. Initial periapical radiographs for diagnosis and treatment planning, employing the parallelism technique, were taken. CBCT images were acquired with i-CAT system (aiming of diagnosing the cases of apical periodontitis that showed to be complex and doubtful) and measured with specific function of i-CAT software. The coronal opening was made, the root canals were irrigated with sodium hypochlorite solution 2.5%, being performed the exploration and initial emptying of root canal. After, the preparation of the inlet orifice and of the cervical root third was carried out . The minor foramen was located using Root ZX® locator by advancing a stainless steel K-file that best suited the root canal, according to the manufacturer´s instructions. The radiographic measurement was made by advancing a stainless steel K-file in the root canal, until its tip was 1.0 mm from the root apex (determined from the measures obtained by the electronic ape locator). These 3 working length were tabulated and compared. Kruskal-Wallis test was used to analyze the differences between working lengths methods. The significance was set at &#945;=5%. Results The mean values and standard deviations for working length determination by electronic apex locator, periapical radiograph and CBCT images were 21.5 ± 3.1, 21.32 ± 3, 21.4 ± 2.7, respectively. Significant differences were not verified statistically (P>0.05). Conclusions CBCT images working length determination showed to be as similar as the determinations obtained by using periapical radiograph and electronic apex locator. / Introdução: Estratégias para obtenção do comprimento de trabalho para preparar e obturar canais radiculares têm sido tema relevante de discussão em Endodontia. O objetivo deste estudo foi comparar in vivo as medidas de comprimento de trabalho do canal radicular determinadas por meio da tomografia computadorizada de feixe cônico (TCFC) com as obtidas por meio de radiografia periapical e localizador apical eletrônico. Metodologia: Foram avaliados os comprimentos de trabalho dos canais radiculares em 30 dentes de 19 pacientes com diagnóstico de periodontite apical. Radiografias periapicais iniciais de diagnóstico e plano de tratamento, empregando a técnica do paralelismo, foram realizadas. As imagens de TCFC foram obtidas usando o sistema i-CAT (com o intuito de diagnosticar os casos de periodontite apical que se mostraram complexos ou duvidosos) e foram medidas a partir de função específica do programa desse sistema. Foi realizada a abertura coronária, os canais radiculares foram irrigados solução de hipoclorito de sódio a 2,5%, sendo realizada a exploração e o esvaziamento inicial do canal radicular. Depois foi realizado o preparo do orifício de entrada e do terço cervical da raiz. O forame apical foi localizado usando o localizador Root ZX® por meio do avanço de uma lima tipo K-file que melhor se adaptasse ao canal radicular de aço inoxidável no canal radicular, de acordo com instruções do fabricante. A medida radiográfica foi feita por meio da colocação de uma lima tipo K-file de aço inoxidável no canal radicular, até que sua ponta estivesse a 1,0mm do ápice radicular (determinado pelas medidas obtidas com o localizador apical eletrônico). Essas três medidas de comprimento de trabalho foram tabuladas e comparadas. O teste de Kruskal-Wallis foi empregado para analisar as diferenças entre os métodos de obtenção dos comprimentos de trabalho. O nível de significância foi estabelecido em &#945;=5%. Resultados: O valor médio e os desvios-padrões para a determinação do comprimento de trabalho por meio de imagens de TCFC, localizador apical eletrônico e radiografia periapical foram de e 21,4 ± 2,7, 21,5 ± 3,1, 21,32 ± 3, respectivamente. Diferenças significantes entre as medidas obtidas pelos três métodos não foram verificadas (p>0.05). Conclusões: A determinação do comprimento de trabalho em imagens de TCFC mostrou ser tão similar quanto às determinações obtidas por meio do método radiográfico e do localizador apical eletrônico.

Syfte: Att granska hur väl indikatorbilden och rotfyllningsbilden överensstämmer utifrån mätningar med elektronisk apexlokalisator. Dessutom granskas om rotfyllningskvalitet är beroende av tandtyp och antal besök samt om det förekommer någon skillnad på behandlingsproceduren före eller under COVID-19 pandemin. Vidare granskas tecken på läkning i de fall där läkningsbild finns.  Material och metod: Totalt har 635 patienter fått endodontisk behandling på studentklinik för endodonti på Malmö Tandvårdshögskola under perioden 2016–2021. Av dessa uppfyllde 350 journaler inklusionskriterierna. Journaldata tillsammans med röntgenbilder granskades av två oberoende observatörer. Resultat: Av 350 tänder överensstämde 262 tänders indikatorbild och rotfyllningsbild med EAL-mätningar. Underkäksmolarer till följd av överkäksmolarer och överkäkpresmolarer som hade inadekvat rotfyllningskvalitet.  Cirka 70% av tänderna som behandlades färdigt krävde mellan 2–6 besök. Tecken på läkning kunde observeras hos 78 patienter (ca. 92 %) som följts med klinisk undersökning och läkningsbilder. Inga märkbara skillnader noterades i behandlingsproceduren före eller under Covid-19 pandemin. Slutsats: Rotfyllningarna uppvisade god kvalitet baserat på kliniskt och röntgenologiskt underlag. Studenterna behöver relativt många besök för att genomföra en endodontisk behandling. Behandlingen resulterar ofta i en rotfyllning som bedöms ha god kvalitet och så många fall läker. Det behövs ges tydligare rekommendationer till studenter gällande bestämning av arbetslängden och information om att EAL är mer pålitlig att fastställa arbetslängd. / Aim: To evaluate how well the working length radiograph and obturation radiograph corresponded with the working length (WL) measured initially by electronic apex locator (EAL). Furthermore, the aim of this study was to evaluate if the quality of root canal fillings was dependent on tooth type, number of dental visits and if there was any different in treatment procedure before and during the Covid-19 pandemic. Additionally, signs of healing were evaluated if radiographs were available.  Material and method: Patient journal and intraoral radiographs of 635 patients who had undergone endodontic treatment by students at the Faculty of Odontology at University of Malmö during 2016–2021 were evaluated. A total number of 350 patients fulfilled the inclusion’s criteria. Patient’s journal and radiographs were reviewed by two independent observers.  Results: Of 350 teeth, in 262 teeth working length radiograph and obturation radiograph was consistent with the working length determined by EAL. Mandibular morals followed by maxillary molars and premolars were tooth types that failed to keep WL measured by EAL. Approximately 70% teeth were treated between 2-6 visits. In 84 cases radiographs were available and signs of healing were observed in 78 cases (approx. 92%). No significant differences were observed in treatment procedure before and under the Covid-19 pandemic.   Conclusion: The root canal fillings were of good quality based on clinical and radiographic evidence. Students need more time to carry out endodontic treatment but, in most cases, root canal fillings were of good quality and periapical healing was obtained. Furthermore, the students need clearer recommendations regarding determination of WL.

Topologieoptimierte Geometrie wird vom Konstrukteur in einem Format benötigt, das im CAD verwendet werden kann. Die Herausforderung ist, dass man als Optimierungsergebnis eine STL-Geometrie bekommt, doch fürs CAD soll die Oberfläche möglichst glatt und vereinfacht sein. Die Software MSC Apex erzeugt aus einer STL-Geometrie eine echte, geglättete Parasolid-Geometrie. Eine spezielle Form der Topologieoptimierung ist die Topometrieoptimierung, welche die Rippenstruktur auf einem Blech vorschlägt. Auch hierfür ist Geometrierückführung möglich. Auch stark verformte Bauteile, z.B. Gummiteile, kann man als Geometrie im verformten Zustand ans CAD zurückgeben, um zu sehen, wie sie dann in die Baugruppe passen. / Topology optimized geometry must be provided to the designer in a format that can be used in CAD. The challenge is that the optimization result is typically an STL geometry, but for CAD the surface should be as smooth and simplified as possible. The MSC Apex software creates a real, smoothed parasolid geometry from an STL geometry. A special form of topology optimization is topometry optimization, which suggests the rib structure on a sheet. Reverse engineering is also possible for this. Even heavily deformed components, e.g. rubber parts, can be returned to CAD as geometry in the deformed state, to see how they fit into the assembly in this state.

L'impact anthropique sur les écosystèmes coralliens est aujourd'hui largement documenté, que ce soit sur la biodiversité qu'ils hébergent, leur diversité fonctionnelle, les services écosystémiques qu'ils procurent ou leur capacité de résilience. Parmi les groupes trophiques, les prédateurs apicaux en général et les requins en particulier, sont particulièrement sensibles aux perturbations d’origine humaine du fait de leurs traits d'histoire de vie conservateurs (e.g. croissance lente, maturité sexuelle tardive, faible fécondité). D'après certaines estimations, les populations de requins ont décliné de plus de 90% à l'échelle globale. Afin d'assurer le maintien de leurs populations et de leur rôle fonctionnel dans la communauté, il est nécessaire de mettre en place des mesures de gestion adaptées. Les objectifs de cette thèse sont de 1) faire le bilan des populations de requins de Nouvelle-Calédonie ; 2) déterminer l'efficacité des vidéos stéréoscopiques appâtées (S-BRUVS) pour recenser les requins en les comparant aux comptages en plongées (UVC) et évaluer leur possible amélioration ; 3) évaluer l'impact de la proximité humaine sur la diversité, l'abondance et le comportement des requins récifaux et 4) déterminer l'efficacité des mesures de gestion en place pour protéger ces espèces emblématiques. Les résultats des deux méthodes de recensement montrent un important déclin d'environ 90% des abondances de requins récifaux le long d'un gradient anthropique complet en Nouvelle-Calédonie alors que la pêche des requins est historiquement absente dans cet archipel. Une importante altération comportementale du requin gris de récif (Carcharhinus amblyrhynchos) face à la nouveauté d'un appât a été mise en évidence. Les individus se tiennent plus éloigné du dispositif, interagissent moins avec l'appât et mettent plus de temps pour le mordre avec l'augmentation de la proximité humaine. Cette dernière est le principal moteur de ce déclin d’abondance (46 à 71%) et de l'altération comportementale vers des individus plus craintifs (50 à 80%). Globalement, les aires marines protégées de Nouvelle-Calédonie ne sont pas efficaces pour la protection des requins. Néanmoins, la réserve intégrale Merlet héberge des populations de requins proche du niveau de récifs isolés de l’archipel et protège une partie du comportement. Les résultats de ce travail révèlent 1) l'importance et le caractère unique des récifs coralliens isolés ; 2) qu'en absence de pêche la proximité humaine conditionne l'abondance et le comportement des requins de récifs avec des conséquences écologiques potentielles sur l'ensemble du réseau trophique ; 3) que l'efficacité des AMPs réside dans leur capacité à exclure la présence humaine sur une surface suffisamment grande. / Anthropogenic impacts on coral reefs are largely documented through changes in functional diversity, ecosystem services or resilience. Among trophic groups, apex predators in general and sharks in particular are the most sensitive to disturbance due to conservative life history traits (e.g. slow growth, late sexual maturity, low fecundity). By some estimates, shark populations have declined by >90% worldwide. To ensure the sustainability of their populations and their functional role in the reef community, appropriate management measures must be implemented. The aims of this thesis are 1) to assess reef shark populations in New Caledonia; 2) to evaluate the efficiency of stereo baited remote underwater video systems (S-BRUVS) in surveying shark distribution comparing them to underwater visual censuses (UVC) and to evaluate their potential improvements ; 3) to evaluate the impact of human proximity on diversity, abundance and behaviour of reef sharks and 4) to determine the efficiency of management measures currently in place in New Caledonia to protect reef shark populations. The results of S-BRUVS and UVC were congruent and revealed a dramatic decline of shark abundance of ~90% along the anthropogenic gradient in a country where shark fishing is historically absent. An important behavioural alteration of the grey reef shark (Carcharhinus amblyrhynchos) towards bait was highlighted. Individuals remained farther from the device, exhibited more cautious approaches, interacted less with the bait and took longer to bite it as human proximity increased. Human proximity was the main driver of the abundance decline (46 to 71%) and the behavioural alteration towards shier individuals (50 to 80%). Globally, MPAs in New Caledonia are not effective in protecting reef sharks. However, the oldest and most restrictive MPA (Merlet) hosts shark abundance close to that of some remote reefs of the archipelago and partially protect the behaviour of individuals. These results 1) emphasize the unique role of remote coral reefs as the last refuges for sharks ; 2) reveal that in absence of shark fishing, human proximity condition shark abundance and behaviour with potential ecological consequences and 3) indicate that the MPAs efficiency to ensure the protection of reef sharks is effected by their ability to exclude human presence over a sufficiently large area.