Le profil de dépôt syn-rift d’un Gilbert-delta et de son prodelta du Pléistocène moyen est documenté dans le Rift de Corinthe en Grèce, à partir d’études de terrain et d’un modèle photogrammétrique. Les études de terrain ont permis de mettre en évidence quatre typologies de bottomsets avec des facies, des associations de facies et des géométries spécifiques : (1) des bottomsets de sables et de graviers, (2) un épisode d’érosion et de bypass, (3) un bottomset de sables fins et de silts, (4) un bottomset de sables massifs. Ces typologies sont intégrées dans le cadre stratigraphique du delta. Dans le prodelta associé, deux moats actifs remplis de sables et de conglomérats sont limités par un drift confiné. L’axe des moats migre à contre pente et est perpendiculaire au delta. Dans l’axe des moats, une séquence normale est remaniée en une séquence inverse dans la partie avale sous l’action des courants de fond. Le drift asymétrique développe une sediment-wave sur son flanc long avec deux séquences : (1) une séquence turbiditique strato- et grano-décroissante directement sur une surface d’érosion et (2) une séquence contouritique bi-gradationelle avec des rides de courant, des bancs ondulés, de la bioturbation et des encroutements ferrugineux. De nouvelles cartes d’horizon, structurales, morphodésimentaires et d’épaisseurs sont proposées à partir de l’interprétation des données sismiques avec un pas de temps de 100 ka. Ces éléments documentent la formation d’un système mixte contouritique et turbiditique profond dans le Golfe de Corinthe. Au Sud deux systèmes se développent en pied de pente : un système de bottomsets gravitaires et un système de moat érodant et remobilisant les sédiments pour former des drifts. Au Nord, la pente est remaniée en sediment-wave et par des moats perchés qui produisent des plastered drifts. A 0,4 Ma, un système dominé par les coutourites, dans le Golfe de Corinthe, indique une possible ouverture à l’Est et à l’Ouest. / Middle Pleistocene Gilbert-type delta and prodelta in the Rift of Corinth, Greece, are investigated combining field methods and photogrammetric 3D model to document an entire early synrift sedimentological profile. Field works document four different dynamics in Gilbert-type bottomset deposits, each one of which is characterized by a specific range of facies, facies associations and geometries: (1) the sandy-gravelly bottomset, (2) the erosional-bypass stage, (3) the fine-grained bottomset and (4) the massive-sandy bottomset. The bottomset typologies are integrated within the stratigraphic delta context. In the associated prodelta, two active sandy-conglomeratic moats are limited by a confined drift. The prodelta moat axis are perpendicular to the delta and migrate upslope. In the moat axis, a normal-to-inverse grading sequence evolution is correlated down-flow under bottom-current processes. The asymmetric drift presents a sediment-wave architecture on its long side within two sequences : (1) a normal turbidite sequence with a sharp erosional base and massive silt to shale and (2) a contourite bi-gradational sequence affected by red crust, wavy bedding, current ripples and bioturbation. New interpretations of seismic data resulting in horizon, structural, morphosedimentary, and thickness maps, for the offshore Corinth Rift, at a 100 kyr time scales document a mixed turbiditic and contouritic deep water system. The Southern slope break presents a mixed system between gravity-driven bottomset and bottom-current moats which rework and depose drifts. The Northern slope is meanly reworked by sediment-wave and perched drift which can produced plastered drifts. At 0.4 Ma, a contouritic sedimentary system dominates the Gulf of Corinth and indicates an opening at both West and East tips.

SyfteSyftet med denna studie var att undersöka sambandet mellan delta efficiency (DE) i cykling (DEcykel) och löpning (DElöp) för elitaktiva triathleter. Vidare syftade studien till att undersöka om DEcykel och DElöp skiljer sig samt om det är skillnad i DE mellan kvinnliga och manliga triathleter vid respektive aktivitet.MetodFem kvinnliga (22 ± 6 år) och fem manliga (24 ± 5 år) elitaktiva triathleter utförde två submaximala test, ett cykeltest och ett löptest på rullband med konstant lutning på 2,5˚. Hastigheten ökad stegvis med 2,4 km·tim-1 under cykeltestet och 0,6 km·tim-1 under löptestet för respektive intervall á fem minuter för att fastställa DE. DE är förhållandet mellan förändringen i utfört arbete och förändringen i energiförbrukning, presenterat i procent. Triathleterna använde sin personliga cykel- och löputrustning.ResultatDet fanns inget statistiskt samband mellan DEcykel och DElöp för elitaktiva triathleter (p > 0,05). En statistisk signifikant skillnad påvisades mellan DEcykel och DElöp (p < 0,001). Ingen skillnad i varken DEcykel eller DElöp upptäcktes mellan kvinnor och män (båda p > 0,05).SlutsatserTriathleters DEcykel är signifikant högre än DElöp. Det upptäcktes inget samband mellan DEcykel och DElöp bland triathleterna på individnivå vilket innebär att en triathlet med högt värde för DEcykel inte per automatik även har högt värde för DElöp. Ingen könsrelaterad skillnad upptäcktes bland triathleterna. / PurposeThe purpose of the present study was to investigate the relationship between delta efficiency (DE) in cycling (DEcycle) and running (DErun) among elite triathletes. Furthermore, another aim of the study was to investigate if DE differ between the activities and/or gender.MethodsFive elite female (22 ± 6 years) and five elite male (24 ± 5 year) triathletes preformed two submaximal tests, a cycling test and a running test on a motorized treadmill in a constant inclination of 2,5˚. The treadmill speed between stages was increased by 2.4 km·h-1 for the cycling test and 0.6 km·h-1 for the running test. Each stage was five minutes followed by a one minute pause. DE is the relation between the change in work rate (WR) and the change in metabolic rate (MR), presented in percentages. The triathletes own bikes and running equipment were used during the tests.ResultsThe results did not show a relationship between DEcycle and DErun between elite triathletes (p > 0,05). A statistical significant difference was found between DEcycle and DErun (p < 0,001). No gender difference was found for either DEcycle or DErun (both p > 0,05).ConclusionsThe DEcycle were significantly higher among the triathletes compared to DErun. No relationship between DEcycle and DErun were found, which means that triathletes with a grate DEcycle does not automatically have a grate DErun. No gender related difference was discovered between the triathletes.

Les amplificateurs de puissance, éléments constitutifs essentiels de tout système de télécommunication, vont jouer un rôle capital dans le développement des futurs systèmes de communication. Aujourd'hui l'amélioration des amplificateurs de puissance nécessite un progrès technologique au niveau du composant lui même mais doit aussi tenir compte d'une approche plus globale. En particulier, le progrès dans les traitements numériques permet aujourd'hui de corriger en amont certaines distorsions qui seront générées en aval de la chaîne de communication. La pré-distorsion numérique est une technique de correction des amplificateurs de puissance qui connaît un intérêt grandissant de par son intégration complètement numérique et par les gains en linéarité et en consommation. Cette technique nécessite une voie de retour dont un élément critique est le convertisseur analogique-numérique. Ce composant doit répondre à des contraintes de résolution, de bande passante et de linéarité élevées. Dans cette thèse, nous proposons une nouvelle architecture de convertisseur analogique-numérique à base de modulateurs Sigma-Delta passe-bande. Cette architecture tire partie du fonctionnement passe bande des modulateurs que nous faisons travailler en parallèle, chacun centré sur différentes fréquences, mais aussi d'un agencement en cascade particulier pour éliminer le signal utile, qui est de forte puissance, dans le but de diminuer les contraintes de dynamique.La conception haut niveau et les simulations ont été menées pour des systèmes à temps discret et aussi à temps continu et a nécessité le développement d'outils adaptés de simulation se basant sur la boîte à outils Delta Sigma Toolbox de Richard Schreier / Power amplifiers, which are essential elements of any communication system, will play a crucial role in the development of future communication systems. Today improving power amplifiers requires technological advances at the circuit device level, but one also must consider a more global approach. In particular, advances in digital processing can now correct in the early stage of the communication chain some distortions that are generated downstream in the chain. Digital pre-distortion is a correction technique for power amplifiers that has a growing interest because of its completely digital implementation and of its gains in linearity and energy consumption. This technique requires a feedback path where the analog-to-digital converter is a critical element. This component must satisfy the constraints of high resolution , wide bandwidth, and high linearity. In this thesis, we propose a new architecture of analog-to-digital converter based on bandpass Delta-Sigma modulators. This architecture takes advantage of operating bandpass modulators that are designed to work in parallel, each focusing on different frequencies, but also of a particular cascading arrangement to eliminate the useful signal, which has a high power, in order to reduce dynamics constraints. High-level design and simulations were carried out for discrete time and continuous time systems and also required the development of appropriate simulation tools.

Cette thèse porte sur la conception et la réalisation de convertisseurs analogique/numérique (ADC) haute résolution dans le domaine de l’imagerie spatiale en technologie 0.18 μm.Un imageur CMOS est un système destiné à acquérir des informations lumineuses et les convertir en données numériques afin que cellesci soient traitées. Ce système est composé d’une matrice de pixels, d’ADC, de registres et de blocs de signaux de commande afin de rendre toutes ces données disponibles. Avec la taille grandissante de la matrice de pixels et la cadence d’image par seconde croissante, l’ADC doit réaliser de plus en plus de conversions en moins de temps et est donc devenu l’un des « bottleneck » les plus importants dans les systèmes d’imagerie. Une solution adaptée a donc été le développement d’ADC colonne situé en bout de colonnes de pixels afin de réaliser des conversions en parallèles et c’est ce sujet qui va m’intéresser.Dans une première partie, n’ayant pas de contraintes sur l’architecture d’ADC à utiliser, une étude de l’état de l’art des ADC pour l’imagerie est réalisée ainsi que les spécifications visées pour notre application. Une architecture sigma-delta incrémental à deux étapes semble la plus prometteuse et va être développée. Ensuite, une étude théorique de l’ADC choisi, et plus particulièrement du modulateur sigma-delta à utiliser est effectuée, afin notamment de déterminer l’ordre de ce modulateur, mais également le nombre de cycles de cette conversions. Une fois les paramètres de modélisation définis, un schéma transistor est réalisé au niveau transistor, avec une particularité au niveau de l’amplificateur utilisé. En effet, afin de gagner en surface qui est l’un des points importants dans les systèmes d’imagerie, un inverseur est utilisé. Une étude de cette inverseur, afin de choisir le plus adapté à notre besoin est effectuée avec des simulations montecarlo et aux « corners ». Pour finir, un routage global de l’ADC est réalisé afin de pouvoir comparer ces performances à l’état de l’art. / This thesis deals with the conception and design of high resolution analog-to-digital converters (ADC) for CMOS image sensor (CIS) applications with the 0.18 μm technology. A CIS is a system able to convert light to digital data to be processed. This system includes a pixel array, ADCs, registers and a set of clocks to acquire and transport the data. At the beginning, a single ADC was used for the whole matrix of pixels, converting the pixel value in a sequential way. With the growing size of the pixel array and the increasing frame rate, the ADC became one of the bottleneck of these system. A solution was found to use column ADC, located at the bottom of each column in order to parallelize the conversions. These column ADC are going to be my point of interest in this thesis.First of all, a state of the art of the ADC for CIS is realized in order to determine the best architecture to use. A two-step incremental sigma-delta is chosen and investigated. A theoretical analysis is done, especially on the modulator in order to determine the order of this modulator and the oversampling ratio of the conversion. Then a schematic is realized, with a special feature on the amplifier. Indeed, an inverter is used as amplifier in order to reduce the size of the ADC. A montecarlo and corner studies are then realized on the ADC, a layout is proposed and the ADC is compared to the state of the art of the ADC for CIS.

Prior work in the field of set theory has looked at the properties of union-free families. This thesis investigates families based on a different set operation, the symmetricc difference. It provides a complete characterization of maximal symmetric differencefree families of subsets of {1, . . . n}

Stable isotope analysis is often used to evaluate elements of the lives of past peoples, such as diet and health status, at a societal level. Analysis at an individual level is exceptionally rare, and has not been conducted using a variety of tissues representing both early life and life approximate to death. In this study, δ 13C and δ15N isotope signatures are used to create life histories for single individuals from Romano-Christian period Kellis 2 cemetery in the Dakhleh Oasis, Egypt. Samples are obtained from several different tissues, including tooth dentin, bone collagen, hair, nail, skin, and gut content, all of which have been previously researched, but have not been studied at such an individualistic level. By using data and previous research conducted by Drs. Tosha Dupras and Lana Williams, this research uses isotopic values from the aforementioned tissues, and the differing turnover rates of these tissues, to develop lifetime timetables for 15 individuals (female, male, and juvenile). Results show that individual analysis is possible, informative, and can enlighten researchers not just concerning the individual, but about the population as a whole. The methods presented can serve as a model for reconstructing individual life histories using isotope data from multiple tissues.

No description available.

Meyer’s Parrot Poicephalus meyeri is the smallest of the nine Poicephalus parrots, forming the P. meyeri superspecies complex with five congeners. Their distributional range far exceeds any other African parrot, extending throughout subtropical Africa. Meyer’s Parrots had previously not been studied in the wild, and therefore, gathering high-quality empirical data on their behavioural ecology became a research and conservation priority. The primary aim of the study was to correlate environmental (e.g. rainfall, habitat availability, resource characteristics, food resource abundance and temperature) and social (e.g. inter- and intra-specific competition, predation, and human disturbance) variables with aspects of their ecology (e.g. flight activity, food item preferences, breeding activity, and group dynamics) to evaluate the degree of specialization in resource use (e.g. trophic, nesting and habitat niche metrics). African deforestation rates are the highest in the world, resulting in twelve out of the eighteen Meyer’s Parrot range states undergoing drastic loss of forest cover over the last 25 years. Most commentary on the population status of Meyer’s Parrots and other Poicephalus parrots pre-dates this period of rapid deforestation In addition, over 75 000 wild-caught Meyer’s Parrots and almost 1 million wild-caught Poicephalus parrots have been recorded in international trade since 1975. Empirical data from this study was used to identify ecological weaknesses (e.g. niche specialization or low breeding turnover) for evaluation within the context of deforestation in the African subtropics. Baseline data on the breeding biology and nest cavity requirements of Meyer’s Parrots was also necessary to assess the viability of applying the conservative sustained-harvest model to African parrots. A unifying goal of this study was to advance our knowledge of the ecology of African parrots and other Psittaciformes by assessing the validity of current hypotheses put forward in the literature. The Meyer’s Parrot Project was initiated in January 2004 on Vundumtiki Island in the north-eastern part of the Okavango Delta, Botswana. Due to high flood waters between March and July 2004, road transects were postponed till August 2004. Transects were conducted at Vundumtiki from August 2004 to July 2005 and February 2007 to August 2007, and at Mombo from August 2005 to January 2006. During 480 road transects over 24 months, food item preferences closely tracked fruiting and flowering phenology, resulting in significant positive correlations between Levins’ niche breadth, rainfall and food resource availability. Meyer’s Parrot can, therefore, be considered opportunistic generalists predispersal seed predator that tracks resource availability across a wide suite of potential food items, including 71 different food items from 37 tree species in 16 families. Meyer’s Parrots were, however, found to be habitat specialists preferring established galleries of riverine forest and associated Acacia-Combretum marginal woodland. These strong habitat associations facilitate their wide distribution throughout the Kavango Basin, Linyanti Swamps, down the Zambezi valley, up along the Rift Valley system in associations with the great lakes, through the Upper Nile and the Sudd, and west as far as Lake Chad through the Sahel. Seventy-five nest cavities were measured during this study, including 28 nest cavities utilized by Meyer’s Parrots within the 430ha sample area at Vundumtiki. Over 1700 hours of intensive nest observations at six nest cavities was undertaken. Meyer’s Parrots formed socially monogamous pair-bonds maintained over at least four breeding seasons. Breeding pairs established breeding territories up to an estimated 160ha within which there were 1–6 nest cavities. Eggs hatched asynchronously, yet nestlings fledged synchronously with similar body size and condition. There was evidence to support the incidence of extra-pair copulations, however, mitochondrial DNA sequence data are required to confirm the incidence of extra-pair fertilizations. Meyer’s Parrots had no preferences in regard to nest tree species beyond the incidence of suitable nest cavities, which are selected and further excavated to accommodate their non-random nest cavity preferences. There was a significant non-nesting Meyer’s Parrot population during the breeding season, likely due to this longlived cavity-nester delaying nesting until a suitable breeding territory becomes available. Meyer’s Parrots utilize communal roosts during summer and disperse from them according to the Foraging Dispersal Hypothesis. Due to the requirement to roost during the middle of the day to avoid heat stress, Meyer’s Parrots have bimodal flight and feeding activity patterns. The highest probability of locating Meyer’s Parrots is between 08h30 and 11h00 during summer when both adults are feeding on the seeds of fleshy-fruits in riverine forest communities. Due to the paucity of data on the current distribution and population status of Meyer’s Parrots and other African parrots, a continent-wide survey of all African parrots represents a conservation priority. Current deforestation rates in several Meyer’s Parrot range, their specialist habitat associations, and lack of evidence to support adaptability to a changing landscape mosaic necessitate the re-classification of Meyer’s Parrots as data deficient or nearthreatened. Based on low breeding population due to limited breeding opportunities, the CITES Appendix II wild-caught bird trade should also be halted until the sustainability of this trade has been evaluated and the relevant information made available. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

This thesis presents an evaluation of the dispersive solid-phase extraction (d-SPE) method referred to as the quick, easy, cheap, effective, rugged and safe (QuEChERS) method for the determination of four organochlorine pesticide residues in fish samples. The pesticides investigated in this study were o, p′-DDT, p, p′-DDE, aldrin and dieldrin. The combined use of Gas Chromatography with an Electron Capture Detector (GC-ECD) and sensitive Time of Flight (TOF) mass detector facilitated the identification of the target analytes. In the absence of certified reference material, the overall analytical procedure was validated by systematic recovery experiments on spiked samples at three levels of 2, 5 and 10 ng/g. The targeted compounds were successfully extracted and their recovery ranged from 76 to 96% with relative standard deviations of less than 13%. The optimum QuEChERS conditions were 2g of fish powder, 10 ml acetonitrile and 1 min shaking time. The optimal conditions were applied to assess the levels of chlorinated pesticides in blunt-tooth catfish (Clarias ngamensis), tigerfish (Hydrocynus vittatus), Oreochromis andersonii and red-breasted tilapia (Tilapia rendalli) from the Okavango Delta, Botswana. Dieldrin, p, p′-DDE and aldrin were detected in all the analysed samples with a concentration range of 0.04 – 0.29, 0.07 – 0.33, 0.04 – 0.28 and 0.03 – 0.24 ng/g per dry weight in O. andersonii, C. ngamensis, T. rendalli and H. vittatus respectively. These concentrations were below the US-EPA 0.1 μg/g allowable limit in edible fish and the Australian Maximum Residue Limit (MRL) of 50 - 1000 ng/g in fresh fish. DDT was not detected in all the fish species investigated. The mean lipid content recorded in the fish samples were 1.24, 2.16, 2.18 and 4.21% for H. vittatus, T. rendalli, O. andersonni and C. ngamensis respectively. No systematic trend was observed between fish age and pesticide levels in fish. Acetylcholinesterase (AChE) activity assays were performed to assess the effects of organochlorine pesticides in Clarias ngamensis. The enzyme activity recorded in Clarias ngamensis from the Okavango Delta and the reference site was 12.31 μmol of acetylcholine iodide hydrolysed/min/g brain tissue. The enzyme activity remained the same indicating no enzyme inhibition. The conclusions drawn from this study are that the QuEChERS method is applicable for the determination of organochlorine pesticide residues in fish matrices. The fish from the Okavango Delta are safe for human consumption.

Les changements climatiques, au niveau de la variabilité du climat, se font ressentir un peu partout à travers le globe que ce soit par le décalage des saisons, une variation des précipitations ou l'augmentation des températures. Certaines régions telles que le delta du Gange-Brahmapoutre-Meghna subissent au quotidien les impacts de ces variations. Quatre grandes perturbations environnementales chamboulent cette dynamique dans cette grande région du delta du GANGE-BRAHMAPOUTRE-MEGHNA : le changement du régime des précipitations, la fonte des glaciers causée par la hausse des températures moyennes annuelles, l'augmentation du niveau marin moyen et les perturbations climatiques extrêmes ponctuelles. Ces perturbations transforment le trait de côte, d'une manière directe ou indirecte. Cette fragilité des berges devient problématique dans un environnement urbain à forte densité. Nos résultats mettent en évidence que, dans un contexte de variabilité climatique changeant et de densité de population croissante, la région du delta du GANGE-BRAHMAPOUTRE-MEGHNA souffre d'une perte de terre viable entraînant des déplacements de populations. Certaines villes ont connu une augmentation de leur population allant au-delà de 1000% sur la période de 1921-2011. L'analyse de photographies aériennes sur la période 2001- 2013 montre un accroissement de l'étendue des zones urbaines, mais aussi du mouvement des berges. Sur une période plus récente, on constate même que de nouveaux quartiers ont été construits dans les zones inondées de 2004.