High-resolution Holocene sediment cores from the continental shelf of Antarctica are integral to the study of recent climate transitions, but such records are rare. The inaugural SHALDRIL I cruise to Maxwell Bay along the Northern Antarctica Peninsula, however, recovered the most expanded record to date at Site NBP05-02-1B. More than twice as long as any other such Antarctic sequence, the 108.2 m section dates back 13,480 yr B.P. Presented here is a record of climate variation interpreted from analyses of the diatom content. Diatoms have proven to be a useful tool in the study of paleoclimate. Analyses completed here include species diversity, total diatom abundance (valves per gram of sediment), Eucampia antarctica var. antarctica to E. antarctica var. recta ratio, Eucampia index, Chaetoceros resting-spore percent, Chaetoceros hyalochaete to C. vegetative ratio, and Thalassiosira antarctica T2 percentage. The analyses show a continuous sea-ice assemblage with minor fluctuations in response to changing sea-ice conditions. Other than the Thalassiosira antarctica T2 percentage, all analyses show a prominent warming period identified as the Mid-Holocene Climatic Optimum. Thalassiosira antarctica T2 percentage marks a period of deglaciation at approximately 11 ka. This episode of deglaciation has been documented in other studies and is believed to mark the onset of present-day ice conditions. / A Thesis submitted to the Department of Geology in partial fulfillment of the requirements for the degree of Master of Science. / Degree Awarded: Spring Semester, 2008. / Date of Defense: December 6, 2007. / Diatoms, Holocene, Antarctica / Includes bibliographical references. / Sherwood W. Wise, Professor Directing Thesis; Jennifer Georgen, Committee Member; Joseph F. Donoghue, Committee Member.

The purpose of this research was to quantify forest disturbance processes and evaluate the influence of these processes on secondary hardwood forest communities on a section of the Cumberland Plateau in Tennessee. The specific objectives of this study were to: (1) reconstruct the disturbance history of a secondary hardwood forest using species composition, stand structure, tree-ring data, and soil charcoal analyses, (2) quantify canopy gap formation mechanisms, (3) document canopy gap characteristics, and (4) determine the forest response to small-scale disturbance events. This information is useful to understand the importance of localized disturbances on stand development and forest successional patterns. With the exception of one stand-wide disturbance in the early 1980s, the disturbance regime of the forest was characterized by localized, asynchronous events that occurred at variable spatial and temporal scales. Gap-scale disturbance events became frequent after about 40 years of forest development. The presence of soil charcoal indicated that fire had occurred in the Pogue Creek Natural Area in the past, but species composition and a lack of fire-scarred trees indicated that fire had not occurred during the development of the current stand. The majority of canopy gaps were caused by treefall (either windthrow or basal-shear) and half of all gaps were caused by the death of a Quercus individual. Gap ages ranged from 1 to 17 years with a mean of 7 years. Seasonality of death could be accurately determined for 17 gap makers and all but one of these trees died during the growing season. Strong wind associated with convective storms is the most probable disturbance agent in the forest. The fraction of land area in expanded gaps and true canopy gaps was 15% and 6%, respectively. The amount of land area in canopy gaps was highest for younger gaps and generally decreased with increased gap age. Most expanded and true canopy gaps had elliptical shapes and the majority of gaps were oriented perpendicular to slope contours. Significant positive relationships were documented between expanded gap size and the density of saplings, trees, and total stems. Only weak relationships existed between stem diversity and expanded gap size. Most of the canopy gaps documented were projected to close by lateral crown expansion rather than height growth of subcanopy individuals, but gaps still provided a means for understory trees to recruit to larger size classes. Over half of all trees located in true canopy gaps with intermediate crown classifications were Acer saccharum, A. rubrum, or Liriodendron tulipifera. Because the gaps documented were relatively small and close by lateral branch growth of perimeter trees, the most shade-tolerant A. saccharum has the greatest probability of becoming dominant in the canopy under the current disturbance regime. This study indicated that gap-scale disturbance processes have an influence on stand development and successional patterns of secondary hardwood forests in the absence of large-scale events.

The genus Phytophthora includes more than 90 described species infecting over 1000 plant species. Population studies were conducted to investigate the survival and spread of P. capsici in the Peruvian coastal region. A total of 227 P. capsici isolates, recovered at widely distant localities from 2005-2007, were fingerprinted with AFLPs and SNP genotyping. A clonal population (PcPE-1) represented by 221 isolates was found to be distributed throughout the country. Atypical isolates of P. nicotianae were isolated from loquat trees in Peru and nuclear (internal transcribed spacer [ITS], the phenol acid carboxylase gene, and AFLPs) and mitochondrial genotyping (cytochrome oxidase gene [coxI]) identified this species as a hybrid between P. nicotianae and P. cactorum A comparison of five Phytophthora hybrid isolates from Peru and Taiwan (also infecting loquat trees) suggested that isolates from Peru likely originated from a single hybridization event and that the two isolates from Taiwan originated through different hybridization events. The generation of genetic resources for the study of complex genetic traits in P. capsici was initiated by studying its inbreeding up to the sixth generation. A total of 692 oospore-derived isolates were fingerprinted and a subset was characterized for pathogenicity in cucumber and jalapeno fruits and for segregation of the mating type. The traits tested revealed no-Mendelian segregation, and apomixis were observed to be more prevalent (100%) in deep (fifth generation) inbreeding crosses. Inbreeding was measured by studying the segregation of 20 AFLP markers, which indicated a loss of heterozygosity of ~75% by the sixth generation. The seminal cross from this study was used as a mapping population (F1) for generating a genetic linkage framework with 189 AFLP and 18 SNP markers. A total of 18 linkage groups were produced for each parental isolate using 65 and 42 markers for CBS121657 and CBS121656 isolates respectively covering 409 cM. SNP markers FL5 and FL6 were used for estimating the genome size of P. capsici and precision of the genome assembly. In order to conduct functional studies in P. capsici, we tested the efficacy of the polyethylene glycol mediated transformation. We regenerated up to 30 antibiotic resistant isolates and 53% of them were stable after three months of subculturing.

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Rezensiertes Werk: Globalisierung, Region und Regionalisierung / Benno Werlen. - Stuttgart : Steiner, 1997. - XI, 464 S. (Sozialgeographie alltäglicher Regionalisierungen ; Bd. 2; Schriftenreihe Erdkundliches Wissen ; 119) ISBN 3-515-06607-1

Rezensiertes Werk: Zillinger, Sylvia: Regionalwirtschaftlicher Strukturwandel und individuelle Arbeitsplatzproblematik : untersucht am Beispiel der Region Heinsberg und der Zeche Sophia-Jacoba / vorgelegt von Sylvia Zillinger, geb. Peters. - Aachen : Maas-Rhein-Inst. für Angewandte Geographie, 1997. - XII, 382 S. : graph. Darst., Kt. (Informationen und Materialien zur Geographie der Euregio Maas, Rhein : Beiheft ; 7) Zugl.: Aachen, Univ., Diss., 1997