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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Reappraisal of geophysical phenomena and associated portents in the classical world

Maxwell Miller Unknown Date (has links)
ABSTRACT Many unusual phenomena in nature were recorded from the regions bordering the Mediterranean Sea from the second millennium BC up to AD 600. The ancient sources interpreted these as prodigies, messages from the gods, but rarely discussed their causes. Numerous reports of these portents were viewed as the illusions of eyewitnesses or the fabrications of ancient literary sources. Many modern authors have interpreted these portents as fabulous, or as astronomical or meteorological events. This thesis examines the portents that occur in the atmosphere, biosphere, lithosphere and hydrosphere and proposes that many are geophysical phenomena caused by tectonic activity, in particular earthquakes and volcanoes. Modern research on these incidents is examined to identify characteristics and causes, and texts from ancient philosophers and natural historians are investigated to see whether they were aware of these natural occurrences and if so, how they were produced. Portents that possess the characteristics of seismically-induced lights, cloud, fog, storms, anomalous animal behaviour, noises, and hydrological changes are collated in order to discuss individual events. Where possible, ancient examples are compared with modern well-documented episodes with the same features. In a majority of cases, these events have recurred in the same locations at later times. The proposal that many of these phenomena are caused by seismic activity offers an alternative to the suggestions of many modern scholars, who ascribe many of the luminous events to lightning, meteors or comets and some sonics to exploding meteors or thunderstorms. This reappraisal of the ancient portents vindicates the seemingly fantastic reports that occur in the ancient texts, especially some of the poetic or religious sources, and rehabilitates the reputation of the authors who have documented these events. In the process it also adds to the catalogue of geophysical phenomena caused by earthquakes in the classical world.
2

Improving our understanding of evolutionary persistence in an increasingly high CO2 world : insight from marine polychaetes at a low pH vent system

Lucey, Noelle Marie January 2016 (has links)
The main aim of this thesis was to determine how marine metazoans might persist as ocean acidification (OA) conditions intensify. This was done using a combination of field surveys, field transplants and laboratory experiments with polychaetes from a site where volcanically-derived CO2 gas bubbles through the seafloor and drives the seawater pH down, resulting in a marine ecosystem representative of global OA projections for, or before, the year 2100. My first objective was to identify phenotypes, or traits, associated with OA tolerance (Chapter 2 and 5). To do this, I characterized the distribution of dominant calcifying polychaetes along natural pH gradients and used a comparative species recruitment trial to investigate life history traits underlying species’ OA tolerance, or vulnerability. I first found two dominant, closely related species of polychaete: Pileolaria militaris Claparède, 1870 and Simplaria sp. (Serpulidae, Spirorbinae). I then found that increased fecundity and rapid settlement are important traits in determining species’ abilities to persist in low pH environments (Chapter 2). Afterwhich, I investigated the life history traits of the non-calcifying polychaete, Platynereis dumerilii (Audouin & Milne Edwards, 1834), of one of the few species from the low pH site known to have broadcasting, pelagic development. I performed breeding experiments on P. dumerilii collected in both ambient and low pH sites and found that specimens from the low pH site were actually the direct developing brooder sister species, Platynereis massiliensis (Moquin-Tandon, 1869). By reanalayzing the distributions of both species at each site using genetic barcoding, I found clear evidence that direct development and brooding are dominant traits at low pH site, and for OA persistence (Chapter 5). My second objective was to use reciprocal transplant experiments to compare the relative importance of local adaptation and/or plasticity as potential mechanisms responsible for the differential tolerances of populations of the polychaete species Simplaria sp. to low pH. Laboratory transplants indicate that a local adaptation response occurred through genetic accommodation in the Simplaria sp. population from the low pH site. However, neither local adaptation nor plasticity appeared responsible for this species natural low pH persistence when assessed in situ (Chapter 3 & 4). My final objective was to create a framework using the polychaete vent model to identify other types of marine metazoans that are likely to be able to adapt to, and survive, under the predicted environmental conditions (Chapter 5). I overviewed the life history strategies of all dominant polychaetes in the low pH sites, and related trends in their life history strategies to those of other marine invertebrates. Brooding and direct development appear to be key traits for species likely to persist in future oceans pH. I conclude by summarizing how research regarding evolutionary responses may be advanced to add confidence to our projections of future marine metazoan responses.
3

Acoustic Repertoire of Sperm Whale (Physeter macrocephalus) Bachelor Groups in the Waters Surrounding Ischia, Italy (Tyrrhenian Sea)

Ledon, Cristina M. 22 April 2016 (has links)
The subpopulation of sperm whales (Physeter macrocephalus) in the Mediterranean Sea is presently list as “Endangered”. This study is an attempt to provide detailed data on sperm whale Bachelor Groups surrounding Ischia, Italy in the Tyrrhenian Sea (Mediterranean Sea). 24 hours, 38 minutes, and 38 seconds of sperm whale Bachelor Group acoustic data was analyzed in order to describe acoustic repertoire, classify behavioral associations to acoustic types, and identify habitat-use. The data showed that the acoustic repertoire of sperm whale Bachelor Groups is dominated by Usual Clicks. Additionally, a click type that maintains an inter-click interval (ICI) in between Usual Clicks and Creaks was identified during acoustic analysis and named “Transition Clicks”. Acoustic events were categorized into Single Code and Combination Code events; representing situations where one acoustic code was heard versus situations where two or more different acoustic codes were heard simultaneously. Analysis revealed that Single Code events represented 71.25% of the sperm whale Bachelor Group acoustic repertoire. The Usual Click/ Transition Click combination represented 73.74% of Combination Code events. A significant difference was shown between time spent in Single Code versus time spent in Combination Code for Usual Clicks and for Squeals. Acoustic repertoire data revealed the possibility for a strong collaborative acoustic structure and a speculated strategy for evolutionary success among sperm whale Bachelor Groups in Ischia, Italy. Additionally, the study showed that sperm whale Bachelor Groups spend 77.87% of the analyzed time engaged in orientation/searching/foraging behavior and 1.09% engaged in socializing behaviors. Event maps revealed a ‘hotspot’ of sperm whale Bachelor Group activity in the waters to the northwest of Ischia, Italy, within the submarine Canyon of Cuma, and outside of the boundaries for the Regno di Nettuno Marine Protected Area (MPA). It is recommended that the results of this study be utilized in extending the Regno di Nettuno MPA to include the ‘hotspot’, and possible critical area, for sperm whale Bachelor Groups. The results of this study and published literature of the sperm whales in this area could be utilized to create population-specific management strategies for more effective measures in ending population decrease and preserving the species. Further research should be carried out to analyze in detail the role of Transition Clicks in sperm whale acoustics and the possibility of a collaborative acoustic structure that has yet to be displayed in any other sperm whale population worldwide.

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