La thèse examine l'optimalité de la Zone Euro une vingtaine d'années après le débat entre la Commission Européenne puis Frankel et Rose (1998) et Krugman (1993). Elle porte principalement sur les membres fondateurs (1980-2010), et s'intéresse secondairement à l'élargissement de la zone monétaire aux PECO. Elle retient un critère transversal d'analyse: la convergence des cycles économiques des pays membres évoqué dès Mundell (1961). L'analyse de la convergence des cycles (corrélation) et des chocs (modèle SVAR) est complétée par celle des déterminants de la première faite à l'aide de modèles à équations simultanées et de modèles dynamiques sur données de panel, ceci afin de répondre à la question de l'endogénéité des critères d'optimalité et ses conditions de réalisation. Enfin, le cas des biens non échangeables mérite d'être étudié à la lumière des caractéristiques de la crise économique de 2007-2008 qui a fortement touché les pays membres en rattrapage. L'analyse de la synchronisation des cycles immobiliers tient compte des caractéristiques particulières du secteur immobilier. La zone montre des divergences qui s'accentuent à nouveau avec la crise actuelle qui met en cause la viabilité de la monnaie unique ainsi que l'optimalité de la zone monétaire. / We examine the optimality of the euro zone two decades after the debate between the European Commission and Frankel and Rose (1998) versus Krugman (1993). The study focuses on the founding members between 1980 and 2010, and it also deals with the expansion of the currency area to CEECs. We retain a main convergence criterion through the analysis: the convergence of business cycles in member countries [Mundell (1961)]. The analysis of the convergence of cycles (with their bilateral correlations) and shocks at their origin (using a SVAR model) is completed by the study of its determinants (using simultaneous equations models and dynamic panel models). We then address the issue of endogeneity of the optimality criteria and its conditions of realization. Finally, the case of the real estate sector deserves to be studied in light of the characteristics of the economic crisis of 2007 - 2008 which has greatly affected catching up members. The analysis of the housing cycles takes also into account the specific characteristics of the housing sector. The area displays differences that are growing again with the crisis and calls upon the viability of the Euro Zone and the optimal currency area.

Dans le cadre de l'application de la Directive Cadre sur l'Eau il serait intéressant de mettre au point de nouveaux outils de surveillance de la qualité des cours d'eau. Dans le cas d'une pollution ponctuelle, certains d'entre eux pourraient être basés sur l'évaluation de l'état physiologique des communautés de diatomées périphytiques qui constituent souvent le premier maillon des écosystèmes aquatiques continentaux. L'objectif de ce travail était d'étudier l'effet de polluants communément retrouvés dans les milieux aquatiques (Cu, Zn, Cd, atrazine, isoproturon) sur la réponse de communautés périphytiques naturelles et de mieux cerner l'influence de la lumière. Nous avons mis au point une démarche méthodologique originale, basée sur l'estimation de leur activité photosynthétique à l'aide de la technique de mesure de la fluorescence chlorophyllienne en lumière modulée (fluorescence PAM). Nos résultats ont mis en évidence une certaine résistance à court terme des communautés aux différents polluants testés, variable selon le mode d'action du polluant (herbicides vs métaux lourds) et la structure du biofilm (biomasse, composition spécifique). En combinant des expérimentations originales en conditions naturelles et au laboratoire, nous avons montré que l'application d'un stress supplémentaire comme la lumière amplifie de manière significative la toxicité de ces contaminants. Ce travail confirme tout l'intérêt de l'utilisation de la technique de mesure de la fluorescence chlorophyllienne en lumière modulée dans le cadre de bioessais écotoxicologiques. Il offre également des perspectives intéressantes en vue de la détection in situ de pollutions ponctuelles par les herbicides. / Ln the context of the European Water Framework Directive implementation, new tools for river toxicity assessment have to be developed. Periphytic communities, which play a fundamental role in the trophic web in lotic systems, could be regarded as early wamings for detection of acute toxicant exposure by monitoring its physiological state. Several studies were then carried out by means of the chlorophyll fluorescence measurement in modulated light technique (P AM fluorescence) which helps to estimate the photosynthetic activity in a non-intrusive way. The aim of the present work was to study the effects of several pollutants commonly found in aquatic ecosystems (Cu, Zn, Cd, atrazine, isoproturon) on stream periphyton physiology and to highlight the role of light as an addition al potentially stressful parameter. Our results showed a relative resistance of the natural biofilms to the pollutants on a short term scale (< 1 day) which depended both on the mechanism of action of the toxicant (herbicides vs heavy metals) and the biofilms architecture. By combining novel experimental designs both in field and laboratory conditions, we also demonstrated that periphyton can be more affected when another stress, such as light, is applied. This work confmns the usefulness of chlorophyll fluorescence-based methods in ecotoxicological studies, particularly in order to detect in situ herbicide toxic effects.

Low fertiliser recoveries are often found for temperate coniferous forests and appear to be associated with the 'locking-up' of residual fertiliser N in stable organic forms. This phenomenon may well be caused by strong microbial immobilisation, out competing uptake by tree roots. This thesis investigates root/microbe competition for fertiliser-derived N (FDN) in microcosms of coniferous forest soil (supporting Sitka spruce seedlings) as well as in re-seeded blanket peat (supporting a mixed grass pasture). Combinations of selective microbial inhibitors, both with and without either 15N-labelled urea or NH4NO3, were applied to microcosms to selectively inhibit target microbial groups which may be competing with roots for FDN and determine the role of microbial immobilisation as a mechanism controlling N flow to seedlings/herbage. The dynamics of FDN novement into microcosm N pools was also studied in microcosms to which 15N-labelled urea was applied alone. At harvest, plant and soil N pools were analysed for 15N and total N (15 N &'43 14N). The impact of biocide and fertiliser N treatments on concentrations of target and non-target soil organisms were also determined. Biocidal (benlate and to a lesser extent streptomycin) inhibition of soil micro-organisms (particularly fungi) increased the uptake of both urea-derived N and NH4O3 N by Sitka spruce seedlings. Increases were associated with reduced percentages of FDA active hyphae and concentrations of FDN immobilised in the microbial biomass of LFH layer and peaty mineral soil. The results suggest that roots were competing with soil microbes for both fertiliser N forms. In conclusion this study has demonstrated the role of microbial biomass, particularly the dominant fungal component as a major competitive sink for fertiliser N and a major factor contributing to the low efficiency of fertiliser N in temperate coniferous forests. The study also has identified selective biocidal manipulation as a powerful technique for characterising competition between roots and microbes for nutrients in soil.

No description available.

MSc (Med), Faculty of Health Sciences, University of the Witwatersrand / I investigated the relationship between abdominal temperature, physical activity, anogenital swellings, and faecal and urine ovarian steroid hormonal concentrations over the menstrual cycle in baboons in an attempt to devise a reliable non-hormonal physiological indicator to detect ovulation. Using a miniature thermometric data logger surgically implanted in the abdominal cavity and an activity data logger implanted subcutaneously on the trunk, I measured, continuously over six months at a 10 min interval, abdominal temperature and physical activity patterns in four female adult baboons, Papio hamadryas ursinus (12.9-19.9 kg), unrestrained in cages in an indoor animal facility (22-25°C). I monitored menstrual bleeding, and anogenital swelling changes using digital photography, and collected urine and faeces, daily, to ascertain the stage and length of the menstrual cycle. The length of the menstrual cycle, determined from daily observations of menstrual bleeding and anogenital swellings, was 36 ± 2 days (mean ± SD). Baboons exhibited a cyclic change in anogenital swellings, abdominal temperature, physical activity, urine and faecal steroid hormones over the menstrual cycle. Mean 24-h abdominal temperature during the luteal phase was significantly higher (ANOVA, p = 0.04; F (2,9) = 4.7) than during the ovulatory phase, but not different to the follicular phase. Physical activity also followed a similar pattern, with mean 24 h physical activity almost twice as high in the luteal than in the ovulatory phase (ANOVA, p = 0.58; F (2,12) = 5.8). As expected, urine and faecal oestradiol was higher in the follicular than in the luteal phase, while progesterone was higher in the luteal than the follicular phase. Cortisol in both urine and faecal samples did not show any vi recognisable menstrual cycle related pattern. I have characterised correlates of the menstrual cycle in baboons and shown, for the first time, a rhythm of physical activity over the baboon menstrual cycle. I have also shown, from the measurements of abdominal temperature, physical activity, ovarian steroid hormonal concentrations and anogenital swellings, that ovulation in captive unrestrained baboons, and probably also free-living baboons, can be estimated from anogenital swellings or possibly abdominal temperature and physical activity, without the need for hormone measurements.

This work was carried out to compare the endocrine function of ovarian tissue isolated in vitro, in an identical environment between ewes and ewe lambs. Furthermore, to determine whether the differences in endocrine and reproductive function of ewes and ewe lambs are related to differences in the proteomics of corpora lutea, follicles and oocytes. Oestradiol concentrations in tissue cultured in TCM-199 were similar for ewe and ewe lamb follicles collected post slaughter on day 9 to 12 of the oestrous cycle and cultured for different incubation times but increased with increase in follicular size. Oestradiol secretion was greater (P<0.001) for ewe and ewe lamb follicles cultured in media with FCS. Media progesterone concentrations were higher (P<0.001) for ewe than ewe lamb follicles. Progesterone in media and in follicular fluid was increased with increased follicles size. Ewe CL, collected on day 9 to 12 of the oestrous cycle, produced more progesterone than ewe lamb CL when cultured in TCM-199 with or without FCS, PVA, BSA. Proteomics indicated more large spots, in ewe follicular and CL tissue average gels compared with ewe lamb average gels. The protein spots were estimated to be between 45 to 97 kD, in both tissue and age groups, this range of molecular weight could have affected steroid hormone synthesis. (Chapter.3). Ewe and ewe lamb follicles cultured with FSH and LH produced more oestradiol than without, furthermore, oestradiol concentration increased with follicle size. There was no difference in media oestradiol concentration between age groups after 24 h of culture. However, for follicles cultured for 2, 4 or 6 h, concentrations were greater after 4 and 6 h, in ewes than in ewe lambs. Overall ewe lamb follicles produced more progesterone (P<0.001) than ewe follicles when cultured with FSH and LH when cultured for 24 h, but no difference was observed after 2, 4 and 6 hours between ewes and ewe lambs Overall ewe follicles produced more (P<0.002) progesterone than ewe lambs when cultured with different concentration of hCG although there was no difference between ages with respect to oestradiol concentrations. Ewe CL secreted more progesterone (P<0.002) than ewe lamb CL, when cultured for 0 or 24 h. Furthermore, tissue concentrations were greater in ewe CL than ewe lamb CL after incubation in TCM-199, TCM-199 plus BSA, TCM-199 plus FCS and TCM-199 plus PVA. Ewe lamb CL produced more progesterone than ewe CL in medium containing LH when cultured for 2, 4 and 6 hours, but ewes produced more progesterone than lambs when CL were cultured with different concentrations of hCG. Relative to untreated shells, the protein profiles of the ewe follicular shells treated with FSH and LH changed to a greater extent than that of the ewe lambs treated gels in both ages contained more protein spots than control gels. The largest spots were estimated to be between 30 and 97 kDa (Chapter.4). There was no difference between age groups for follicles from ewes and ewe lambs treated with ovagen in oestradiol and progesterone concentrations observed after 2,4, 6 and 8 h of incubation in TCM-199. However, treatment with ovagen plus hCG resulted in higher oestradiol and progesterone concentrations in the media from ewe follicles compared to ewe lambs. Furthermore, there were more protein spots in the range 30 to 66 kDa marker in gels from ewes treated with either ovagen or ovagen plus hCG than for ewe lambs (Chapter 5). Lamb oocytes were smaller than ewe oocytes and developed to a lesser extent in culture. Furthermore, the addition of FCS to TCM-199 caused greater cytoplasmic and nuclear maturation than other media used in this experiment and ewe lamb oocytes have a similar 1D protein bands compared with ewe oocytes, but contained less protein (Chapter 6).

No description available.

Ph. D. (Mechanical Engineering), Faculty of Engineering, University of the Witwatersrand, 1986

Loss of proliferative control is a cornerstone of cancer development, induced by deregulation of mitogenic signalling, insensitivity to anti-proliferative signals and direct changes in cell cycle proteins. In breast cancer these alterations are frequently targeted through cyclins D1 and E, leading to defects in G1/S transition. I have investigated the role of two potential pro-proliferative oncogenes in breast cancer, id1 andwt1. Each protein promotes proliferation in distinct contexts, with unique consquences for breast cancer cells. Using a 3D culture model of non-transformed mammary epithelial cells, I identified that id1 undergoes downregulation via rapid proteosomal degradation and cytoplasmic relocalisation during mammary epithelial morphogenesis. Overexpression of Id1 led to an increase in acinar size via an increase in S phase, and wa dependent on the presence of an intact HLH domain in Id1. Co-expression with the proto-oncogene Bcl2 led to a more disorganised acinar structure, indicating that Id1 overexpression primed the cells for further oncogenic insult. Further, Id1 overexpression was unable to increase acinar size in cyclin D1-/- acini, indicating that Id1 is dependent on cyclin D1 for its proliferative effects. Overall these data identified Id1 as capable of altering the proliferation of normal mammary epithelial cells, a crucial step in early breast carcinogenesis. Wt1 was originally identified as a tumour suppressor, but our data lends support to Wt1 acting as an oncogene in breast cancer. Wt1 is expressed highly in a range of breast cancer cell lines, and is strongly regulated by progestins. Using siRNA, we identified that Wt1 is likely to be a molecular intermediary of progestin as the downregulation of Wt1 mimics a subset of progestin effects on cell proliferation and lipid synthesis. Conversely, the overexpression of the major Wt1 isoform, Wt1 (+/+), led to attenuation of progestin-induced differentiation and growth arrest via maintenance of cyclin D1 levels. The effects of Wt1 overexpression were specific to progestins, and did not affect the actions of anti-estrogens or androgens. Consequently the overexpression of Wt1 (+/+) may disrupt the endocrine response in mammary epithelial cells, and contribute to excess proliferation and failure to differentiate during breast oncogenesis.

Includes bibliographical references.