'A wind of change': changes in position and intensity of the southern hemisphere westerlies during oxygen isotope stages 3, 2 and 1

This thesis investigates past climate change in southern part of the world, and more particularly the mid-latitudes of the Southern Hemisphere using lake sediments. Three different locations within these latitudes were selected for this investigation: 1) Lac d'Armor, a medium-sized lake on the Kerguelen Archipelago (49°S), 2) four large lakes (Lago Villarrica, Lago Calafquén, Lago Panguipulli and Lago Riñihue) in the Chilean Lake District (39-40°S) and 3) Laguna Parrillar, a medium-sized lake in Southern, Chilean Patagonia (53°S). The main focus of this research is to better understand the behaviour of this Southern Westerly wind system during the last 45000 years of the Earth's history. Two type of techniques were used to study these sediments. First of all a seismic survey was performed, with this technique an acoustic image is created of the entire lake basin infill is created. This allows a quasi three dimensional reconstruction of the sediment accumulation in the basin. Consequently the evolutionary history of this basin can be reconstructed. The resolution of this technique is, however, rather low (e.g. millenial time scale). Therefore, short term variations will not be represented in such a record. To bypass this limitation, sediment cores can be taken of the same lake sediment . A sediment core record will not span the same large time span as a seismic record, nor will it allow a three dimensional reconstruction, but it will allow the reconstruction of climatic variations on a high resolution time scale (centennial to decadal scale). Combining both techniques the climatic history of a region can be unraveled in its every aspect. All of these lake sediment archives record changes in the intensity of the Southern Hemisphere Westerlies. When absolute ages are available these changes seem to be rather synchronous at both 39°S and 53°S, therefore not really indicating clear shifts of the Southern Westerlies. There is, however, a slight asynchronous behaviour during the last 1000 years, a period during which the influence of the El Niño Southern Oscillation is strong South Central Chile

Potential of cone penetrating testing for mapping deeply buried palaeolandscapes in the context of archaeological surveys in polder areas

Geoarchaeological mapping of wetlands conventionally involves extensive coring. Especially in wetlands marked by a deep palaeosurface (>3 m deep) this can be very difficult and time-consuming. In this paper we therefore present an alternative approach based on Cone Penetration Testing (CPT) for structured, rapid and cost-effective evaluation of buried palaeolandscapes. Both estuarine and river floodplain environments were investigated, including the watereland transition zone (marsh). The efficiency, reliability and repeatability of the CPT method was tested through the comparison with ground-truth core data. The CPT data generally allowed highly accurate mapping of the palaeotopography of the prehistoric surfaces and the overlying peat sequences. Thin organic-rich clay intercalations within the peat layers could often still be identified. Additional pore pressure, conductivity and seismic velocity data (from CPTU, CPT-C and S-CPT) did not add much crucial information and their main use seems to lie in the added value for near surface geophysical measurements. The results of this research clearly illustrate the importance of CPT information for mapping of palaeolandscapes in archaeology

Synchronisation of sedimentary records using tephra : a postglacial tephrochronological model for the Chilean Lake District

Well-characterised tephra horizons deposited in various sedimentary environments provide a means of synchronising sedimentary archives. The use of tephra as a chronological tool is however still widely underutilised in southern Chile and Argentina. In this study we develop a postglacial tephrochronological model for the Chilean Lake District (ca. 38 to 42 degrees S) by integrating terrestrial and lacustrine records. Tephra deposits preserved in lake sediments record discrete events even if they do not correspond to primary fallout. By combining terrestrial with lacustrine records we obtain the most complete tephrostratigraphic record for the area to date. We present glass geochemical and chronological data for key marker horizons that may be used to synchronise sedimentary archives used for palaeoenvironmental, palaeoclimatological and palaeoseismological purposes. Most volcanoes in the studied segment of the Southern Volcanic Zone, between Llaima and Calbuco, have produced at least one regional marker deposit resulting from a large explosive eruption (magnitude >= 4), some of which now have a significantly improved age estimate (e.g., the 10.5 ka Llaima Pumice eruption from Llaima volcano). Others, including several units from Puyehue-Cordon Caulle, are newly described here. We also find tephra related to the Cha1 eruption from Chaiten volcano in lake sediments up to 400 km north from source. Several clear marker horizons are now identified that should help refine age model reconstructions for various sedimentary archives. Our chronological model suggests three distinct phases of eruptive activity impacting the area, with an early-to-mid-Holocene period of relative quiescence. Extending our tephrochronological framework further south into Patagonia will allow a more detailed evaluation of the controls on the occurrence and magnitude of explosive eruptions throughout the postglacial

Design of an optimized Wilms' tumor 1 (WT1) mRNA construct for enhanced WT1 expression and improved immunogenicity in vitro and in vivo

Tumor antigen-encoding mRNA for dendritic cell (DC)-based vaccination has gained increasing popularity in recent years. Within this context, two main strategies have entered the clinical trial stage: the use of mRNA for ex vivo antigen loading of DCs and the direct application of mRNA as a source of antigen for DCs in vivo. DCs transfected with mRNA-encoding Wilms' tumor 1 (WT1) protein have shown promising clinical results. Using a stepwise approach, we re-engineered a WT1 cDNA-carrying transcription vector to improve the translational characteristics and immunogenicity of the transcribed mRNA. Different modifications were performed: (i) the WT1 sequence was flanked by the lysosomal targeting sequence of dendritic cell lysosomal-associated membrane protein to enhance cytoplasmic expression; (ii) the nuclear localization sequence (NLS) of WT1 was deleted to promote shuttling from the nucleus to the cytoplasm; (iii) the WT1 DNA sequence was optimized in silico to improve translational efficiency; and (iv) this WT1 sequence was cloned into an optimized RNA transcription vector. DCs electroporated with this optimized mRNA showed an improved ability to stimulate WT1-specific T-cell immunity. Furthermore, in a murine model, we were able to show the safety, immunogenicity, and therapeutic activity of this optimized mRNA. This work is relevant for the future development of improved mRNA-based vaccine strategies K