Phragmites australis is a perennial grass presently invading many intertidal and freshwater wetlands throughout much of the Atlantic Coast of North America. The spread of Phragmites into coastal wetlands is in part determined by available freshwater and nutrients, especially nitrogen, within the watershed where Phragmites populations occur. The Eastern Shore of Virginia is an intensive agricultural area, and watershed landcover may play a major role in Phragmites invasion. Forty-five Phragmites patches were sampled in eight VA Eastern Shore mainland watersheds and on a barrier island. Regardless of watershed landcover characteristics, there was little variation in Phragmites australis patch characteristics along the oceanside of the entire Eastern Shore of Virginia. Phragmites is a generalist with broad environmental tolerances. Thus, successful management and eradication plans may have broad scale application for this invasive grass.

Blue catfish, Ictalurus furcatus, are an invasive species in the James River, VA. They produce stridulation sounds and passive acoustic monitoring may prove useful in locating and monitoring their populations. Little is known about their behavior, therefore my goal was to examine agonistic behavior and the use of sound in defending a territory. This thesis consists of two manuscripts: 1) A passive acoustic study of the tidal freshwater James River, 2) An experimental study of agonistic behavior in juvenile Blue catfish, Ictalurus furcatus. The first study showed that three sounds (click, run croak) occurred more often in warmer months than cooler months. The second study showed that Blue catfish utilized a variety of agonistic behaviors in territory defense, with residency status and size having an effect on the type and number of displays used. Stridulation sounds were not present in territorial contests although Blue catfish produce stridulatory pulses when held.

The blue catfish, Ictalurus furcatus, is an invasive species introduced to Virginia in 1974 and is the largest catfish in the United States. Like other Ictalurids, they are capable of producing disturbance calls via stridulation of the pectoral spine. These sounds can be made in air and water, and catfish can be preyed upon by both aerial and underwater predators. I characterized these putative distress calls by recording them in air and in the fish’s natural habitat. Sounds exhibited a wide variation in acoustic parameters relative to fish ontogeny: larger fish produced higher amplitude sounds with lower frequency bands. Sweep and pulse duration increased with fish size, but pulse rate and the number of pulses per sweep decreased. Sounds were more robust in water with a 1400 fold increase in sound pressure compared to air. Frequency response was much more peaked underwater with a considerable amount of high frequency absorption. These sounds appear to be better adapted to water, suggesting that their use in air may be inconsequential.

Understanding movement capabilities of individuals within a landscape is essential to identifying the effects of habitat boundaries on species abundances, ranges, and spread rates. Movement barriers due to habitat fragmentation may reduce mate-finding ability in some species, particularly in heterogeneous landscapes containing low-density populations. This study focuses on the effects of habitat type and edge on mate-finding in an invasive defoliator, the European gypsy moth. Adult European gypsy moth males locate mates by following pheromones released by flightless females. Reduced mate-finding was expected in fields and near forest edges based on geographic variation in invasion rates and pheromone plume dynamics. A male release-recapture experiment using female-baited traps in fields, at forest edges, and in the forest interior showed that mate-finding was highest at forest edges, reduced in fields, and lowest within the forest interior. This suggests that forest edges and moderate habitat fragmentation enhance mate-finding in the gypsy moth.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Cryosurgery is the destruction of undesired biological tissues by freezing. Modern cryosurgery is frequently performed as a minimally-invasive procedure, where multiple hypodermic, needle-shaped cryoprobes are inserted into the target area to be treated. The aim of the cryosurgeon is to maximize cryoinjury within a target region, while minimizing damage to healthy surrounding tissues. There is an undisputed need for temperature-field reconstruction during minimally invasive cryosurgery to help the cryosurgeon achieve this aim. The work presented in this thesis is a part of ongoing project at the Biothermal Technology Laboratory (BTTL), to develop hardware and software tools to accomplish real-time temperature field reconstruction. The goal in this project is two-fold: (i) to develop the hardware necessary for miniature, wireless, implantable temperature sensors, and (ii) to develop mathematical techniques for temperature-field reconstruction in real time, which is the focus of the work presented in this thesis. To accomplish this goal, this study proposes a computational approach for real-time temperature-field reconstruction, combining data obtained from various sensing modalities such as medical imaging, cryoprobe-embedded sensors, and miniature, wireless, implantable sensors. In practice, the proposed approach aims at solving the inverse bioheat transfer problem during cryosurgery, where spatially distributed input data is used to reconstruct the temperature field. Three numerical methods have been developed and are evaluated in the scope of this thesis. The first is based on a quasi-steady approximation of the transient temperature field, which has been termed Temperature Field Reconstruction Method (TFRM). The second method is based on analogy between the fields of temperature and electrical potential, and is thus termed Potential Field Analogy Method (PFAM). The third method is essentially a hybrid of TFRM and PFAM, which has shown superior results. Each of these methods has been benchmarked against a full-scale finite elements analysis using the commercial code ANSYS. Benchmarking results display an average mismatch of less than 2 mm in 2D cases and less than 3 mm in 3D cases for the location of the clinically significance isotherms of -22°C and -45°C. In an advanced stage of numerical methods evaluation, they have been validated against experimental data, previously obtained at the BTTL. Those experiments were conducted on a gelatin solution, using proprietary liquid-nitrogen cryoprobes and a cryoheater to simulate urethral warming. The design of the experiment was aimed at creating a 2D heat-transfer problem. Validation results against experimental data suggest an average mismatch of less than 2 mm, for the hybrid of TFRM + PFAM method, which is of the order of uncertainty in estimating the freezing front location based on ultrasound imaging.

Master of Science / Department of Biology / David C. Hartnett / Invasive plants pose a global threat by changing natural communities and ecosystems in ways that may be irreversible. Marrubium vulgare L. (horehound), native to Eurasia, is an invasive exotic plant found throughout the United States. Little is known about M. vulgare in the U.S. and this study aimed to understand the basic biology, habitat, and population dynamics of M. vulgare in its invasive habitat as well as the role of disturbance in the invasions. Wind Cave National Park (WCNP), an area comprising ponderosa pine and mixed grass prairie vegetation types, was used as the site for this study. In a GPS and GIS mapping study, M. vulgare was found to be significantly associated with prairie dog towns, an Aristida purpurea - Dyssodia papposa (threeawn and fetid marigold) vegetation community (a vegetation type found exclusively on prairie dog towns), and certain types of loamy soils. M. vulgare was rarely found off of prairie dog towns and then only in other disturbed areas such as bison trails or tree falls. Population studies showed M. vulgare populations were mostly stable or slightly decreasing in density (though not significantly) from 2010 to 2011; however, a few of the populations did increase dramatically in density from 2010 to 2011. M. vulgare populations existed in high densities (78.3-322.9 ramets/m2) and in low densities (0.1-2.2 genets/m2) throughout WCNP. Disturbances including prairie dog burrows, bison trails, prairie dog and bison presence, mowing, and percent cover of bare ground were measured in relation to population dynamics. While M. vulgare populations were disturbance dependent, there was no clear relationship between disturbances and population dynamics. Examination of M. vulgare life history traits found that while M. vulgare had relatively low biomass allocation to reproduction as compared to native perennial prairie species, M. vulgare produced an extremely high number of small seeds (estimated 1487/plant). Seedling establishment rates were also high. While not quantified, M. vulgare appears to be effectively dispersed through bison epizoochory. These results help to inform management of M. vulgare populations: minimizing disturbance, decreasing propagule supply, and minimizing dispersal may help to reduce M. vulgare invasions.

M.Tech. (Fine Art) / Unemployment and the crime levels which escalate as a result of it, are very realistic social problems in South Africa and training for job skills and entrepreneurship has become a priority. This study identifies the use of invasive plant fibres as a viable resource for the hand papermaking industry and the development of a new cultural industry. The research' funded by the National Research Foundation (NRF) and the Technikon Research Committee (TRC) has been implemented in an established poverty relief programme called Phumani Paper', which creates jobs especially in rural or impoverished sectors through technology transfer and training. A curriculum is currently being developed for current and future participants of this programme to obtain qualifications in hand papermaking. An investigation has been undertaken to define suitable invasive plant species for the purpose of this research. The investigation included the extent of invasive encroachment, plant identification, methods of control and government legislation. Initially water hyacinth (eichhomia crassipes) was identified as a suitable fibre, but because Phumani Paper supports 21 small paper businesses in seven provinces, research had to be undertaken on several different species found in each of the regions. Species such as moth catcher (Araujia sericifera), milkweed (Asclepias fruticosa), pampas grass (Cortadeira selloana), giant reed (Arundo donax) and bugweed (Solanum mauritianum) have been identified as viable fibres for the hand papermaking industry, due to their fibrous characteristics...

The Rio Grande cichlid (Herichthys cyanoguttatus) has been established in the Greater New Orleans Metropolitan Area (GNOMA) for at least 20 years. It is often the most common fish species in urban canals and has also been found in natural waterways outside of the GNOMA. The effects and potential for further spread of H. cyanoguttatus is uncertain. My research addressed how extensive the cichlids spread in the GNOMA, how H. cyanoguttatus interacted with L. macrochirus, a native fish, and what salinity tolerance this species has. Surveys on Lake Pontchartrain and in the GNOMA indicated that H. cyanoguttatus is well established in urban habitats. These surveys also indicate that H. cyanoguttatus has spread rapidly into Bayou Saint John and City Park in recent years and that H. cyanoguttatus populations were relatively unaffected by Hurricanes Katrina and Rita. There is little evidence that H. cyanoguttatus has become established outside of the GNOMA, but this lack of persistence cannot be explained by abiotic variables I measured. Salinity may be a factor and this was measured in growth trials of H. cyanoguttatus. Salinities up to 16 ppt, however, had no significant effect on H. cyanoguttatus growth. Interspecific behavioral experiments were conducted to examine potential biotic interactions with native fish species. Prior resident trials indicated that H. cyanoguttatus was aggressive whether holding territory or not, and that native bluegill (Lepomis macrochirus) was only aggressive while holding territory. Feeding experiments were performed to examine biotic interactions between H. cyanoguttatus and L. macrochirus. Lepomis macrochirus grew faster than H. cyanoguttatus when inter- and intraspecific trials were compared; however, no significant growth differences were seen when trials were structured with L. macrochirus as prior residents. The major findings of my research are a high salinity tolerance of H. cyanoguttatus, a potential mechanism for H. cyanoguttatus affecting native fishes through aggression as residents and invaders, and the presence of H. cyanoguttatus throughout the GNOMA, before and after the hurricanes.

Each year in the United States, approximately 81 million individuals receive surgeries in which .1% to .2% (20,000 to 40,000/20 million) experience Anesthesia Awareness (AA). More than 50% of the AA cases result in mental distress or Posttraumatic Stress Disorder (PTSD). Because the percentage of AA cases among surgeries makes it appear to be a rare occurrence, and because it has received rather limited research attention, I decided to undertake an interpretative phenomenological analysis to discover AA clients’ perceptions of their counseling experience, and encourage development of therapeutic interventions to meet their needs. The broad research question for my study was how do clients perceive their experience of counseling for trauma related to AA? The context was provided by a review of the literature which focused on trauma and PTSD, AA, clients’ perceptions of counseling, counseling for trauma, and counseling for PTSD. Semi-structured interviews were used to collect data which then was coded to identify emerging themes which were then clustered. The clustered themes were used to answer the broad and specific research questions. Based on the findings of my study, the theme of relational factors of counselors most often emerged as helpful to counseling (e.g., Rogerian- congruence, unconditional positive regard, accurate empathic understanding), whereas, the therapy process, external barriers, and PTSD symptoms most often emerged as hindering to counseling. Implications for counselors and counselor educators include increased understanding and insight regarding AA survivors and the role of relationship when counseling this population which may lead to more effective interventions and expanded professional roles to work with this population.