This thesis examines the extent to which geomorphological change in sub-arctic landscapes may be driven by rapid declines in population over timescales of decades to centuries. Demographic decline driven by disease in pastoral agricultural systems is expected to alter patterns of land use. Using a chronology with 20 visible dated tephra layers from AD 870 to present, 2625 tephra layers were identified in 200 sediment profiles. Rates of sediment accumulation dated by tephra provide a record of erosion in Skaftártunga, South Iceland. The scale of enquiry is that of individual landholdings (5–10 km2) over decades to centuries; in order to tackle questions of resilience and change within coupled socio-ecological systems larger and smaller spatial scales (regions of 400 km2 and individual sediment profiles) and longer and shorter temporal scales (2.6 ka and years to decades) are also considered. The novel application of photogrammetric techniques to recording stratigraphic sections increases the frequency of measurement from tens to hundreds per stratigraphic unit and the resolution from ±2.5 mm to ±1 mm. This technique improves the accuracy of representative measures of sediment accumulation and their use in measuring landscape change. Two little known 15th century AD Grímsvötn tephras are mapped and dated to AD 1432±5 and AD 1457± 5 using sediment accumulation rates. A period of landscape stability from AD 1389–1597 is consistent with reduced grazing pressure due to population declines of more than 30% after plague in AD 1402–1404 and AD 1494. Climatic deterioration from AD 1450-1500 does not increase erosion as much as expected; this may be due to decreased grazing pressure after population decline in the 15th century. Increased erosion from AD 935–1262 is related to woodland clearance and increases in sediment accumulation post AD 1625 are related to climatic cooling during the Little Ice age and the migration of erosion fronts into deep lowland sediments.

Dissertation (Ph. D.) -- University of Texas Southwestern Medical Center at Dallas, 2006. / Vita. Bibliography: pp. 221-242.

Inaug. Diss.--Frankfurt am Main. / Lebenslauf. Bibliography: leaves xii-xx.

Thesis (Ph. D.)--Catholic University of America, 1933. / Latin and English. Description based on print version record. "Select bibliography": p. ix-xii.

Thesis (Ph. D.)--Northeastern University, 2008. / Title from title page (viewed March 26, 2009). Graduate School of Arts and Sciences, Dept. of English. Includes bibliographical references (p. 189-204).

No description available.

Aphanomyces spp. are water moulds, eukaryotic fungus-like organisms, belonging to the class Oomycota. This genus contains primary pathogens of plants and animals as well as opportunistic and saprotrophic species. One of the animal parasites (A. astaci) is the causal agent of the crayfish plague, a disease listed by the World Organisation for Animal Health (OIE). It is believed that A. astaci was first introduced into Italy from the US in the late 19th century and rapidly spread in Europe causing the decline of native crayfish. It currently threatens to wipe out the UK native white-clawed crayfish (Austropotamobius pallipes). Random amplified polymorphic DNA (RAPD-PCR) on pure isolates of A. astaci distinguished five genotypes (A, B, C, D, and E). This distinction proved to be a useful tool for epidemiological studies aimed at understanding the history and spread of the disease in Europe; furthermore, there are differences in virulence among genotypes. No discriminatory morphological or physiological characters are available and widely used markers such as the internal transcribed spacer (ITS), the divergent domains regions (D1-D2) of nuclear large subunit (LSU) rDNA, and cytochrome c oxidase subunit I (COI) also fail to discriminate between A. astaci genotypes. There are some practical drawbacks to genotype by the currently available genotyping methods. Whole genome sequencing (WGS) was used to catalogue DNA single nucleotide variants and genotype-unique genomic regions that could be exploited as phylogenetic markers. These newly developed molecular markers were tested both on pure cultures and historical samples derived from outbreaks and carrier crayfish available in our laboratories, validating these genotyping methods, which represent new diagnostic tools aiding the detection and prevention of crayfish plague.

The causative agents of plague (Y. pestis), glanders (B. mallei) and melioidosis (B. pseudomallei) are included in critical agents of bioterrorisim. They belong to the most intensively studied agents during cold war, specially in the former Soviet Union (FSU). Mostly what is known about these agents, particularly (Y. pestis ) is not available in English language publications. Many of the studies are written in Russian language and published in Russian scientific journals. Thus, the work is designed to evaluate, published and unpublished Russian language written data obtained, in comparisions to the current state of global knowledge on the pathogens in concern.

Pr. - Lyceum zu Dillingen. / Includes bibliographical references.

Thesis (Ph. D.)--University of Pennsylvania, 1989. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.