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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.
161

Spatial Ecology of Inter- and Post-nesting Green Turtles (Chelonia mydas) on Bioko Island, Equatorial Guinea

Emily K Mettler (6620087) 10 June 2019 (has links)
<p>Effective conservation strategies for sea turtles require knowledge of animal movements and protection of biologically important habitats and life history stages. For breeding adult sea turtles, understanding both their inshore and pelagic spatial patterns is imperative to the successful protection of the species and the accurate identification of their vulnerabilities. This study provides insight into the inter-nesting, post-nesting, and foraging movements of green sea turtles (<i>Chelonia mydas</i>) that nest on Bioko Island, Equatorial Guinea, by using satellite telemetry to track green turtles (n=12) during two nesting seasons (2017-18, 2018-19), and as they migrated to foraging grounds after the nesting season. These tracks were fit with a switching state space model to characterize movements, and then analyzed in relation to environmental and anthropogenic factors. Dive depth data was also used to determine utilization patterns within the water column. The 12 tagged turtles migrated for an average of 1064 km to two distinct foraging grounds, with 10 migrating west for an average of 1115 km to the coastal waters of Ghana, and 2 migrating south for an average of 1563 km to the coastal waters of Angola. Migrating turtles used both direct, pelagic migration strategies, and biphasal, coastal strategies, which included intermittent foraging throughout migrations. Dive depths varied depending on behavior, with an average of 19.3 m during inter-nesting, 12.6 m during migration and 8.5 m during foraging. Knowledge of inter-nesting habitat use, migration patterns, and foraging ground locations will be critical for the development of marine conservation management plans in the Gulf of Guinea and aide in sea turtle conservation efforts throughout the area. Additionally, spatial and dive depth data can inform zonal fishing regulators and provide information needed for modifications to fishing practices and gear that is most likely to reduce sea turtle bycatch. These data will provide a more complete understanding of marine areas critical to sea turtle conservation and aide in sustainable economic development in the Gulf of Guinea.</p><br>
162

An analysis of phonotactic behaviour in the cricket Gryllus bimaculatus

Sarmiento-Ponce, Edith Julieta January 2019 (has links)
This thesis represents a comprehensive examination of the phonotactic behaviour (i.e. attraction to sound) of the female Gryllus bimaculatus under laboratory conditions. Chapter 2 is the first study to analyze the effect of substrate texture on walking performance in crickets. Substrate texture is found to play an essential role in the phonotactic responses of G. bimaculatus. Smooth substrate texture has a detrimental effect due to slipping, whereas a rough texture results in optimal walking performance due to the friction with the walking legs. Chapter 3 represents the first detailed lifetime study analysing phonotaxis in crickets. My results demonstrate that the optimal age to test phonotaxis in G. bimaculatus females is from day 7 to 24 after the final moult. I also found that selectiveness was persistent with age. These findings contradict the female choosiness hypothesis. This study is also the first to describe the effect of senescence on phonotaxis in insects, as responsiveness decreases with age. Chapter 4 compares the phonotactic behaviour of female crickets from different laboratory-bred colonies. From six tested cricket lab colonies, I found three groups statistically different from each other. Females raised under laboratory conditions at the University of Cambridge and Anglia Ruskin University were most reponsive at a frequency of 4.5 kHz, whereas females bred in Tokushima University in Japan were tuned towards a higher frequency of 5 kHz. These results suggest a degree of artificial allopatric speciation. Comparisons with crickets bred under low-quality conditions in a local pet shop demonstrate a loss of responsiveness, indicating that breeding conditions have a direct effect on phonotactic responsivity. Chapter 5 is the first study to report the presence of phonotaxis in males of G. bimaculatus. Previously it was unknown if G. bimaculatus males were able to perform phonotaxis, given that they were only recognised as endurance signal producers. In the present study, only 20% of the studied males (N=70) performed a weak phonotactic response. This finding has potential ecological implications in terms of male cricket territory establishment, and male-male interactions in the wild, which are discussed. Chapter 6 explores the song pattern recognition of the female G. bimaculatus by changing the duration of either the first, second or third pulse of the chirps. A long first pulse decreased the phonotactic response whereas phonotaxis remained strong when the third pulse was long. Chirps with three pulses of increasing duration of 5, 20 and 50 ms elicited phonotaxis, but the chirps were not attractive when played in reverse order. The data are in agreement with a mechanism in which processing of a sound pulse has an effect on the processing of the subsequent pulse, as outlined in the flow of activity in a delay-line and coincidence-detector circuit.
163

Advancing pain research and animal welfare: focusing on the Rat Grimace Scale and reporting standards

Leung, Vivian 10 1900 (has links)
No description available.
164

DEPREDATION OF OLIVE RIDLEY AND LOGGERHEAD TURTLE CLUTCHES ON BEACHES WITH AND WITHOUT PREDATOR MANAGEMNT

Carlynn Nicole Cornhill (11002167) 23 July 2021 (has links)
<p>Management of predation on sea turtle nesting beaches is vital to conservation efforts for the vulnerable loggerhead turtles (<i>Caretta caretta</i>) and olive ridley turtles (<i>Lepidochelys olivacea</i>). Sea turtles increasingly face threats from invasive and human-tolerant mammalian predators as human disturbances on nesting beaches rises. The intensity of mammalian predation has increased in Las Baulas National Park in Costa Rica which is an important nesting site for several species of threatened and endangered sea turtles. I analyzed loggerhead and olive ridley nest predation on four beaches in the United States and Costa Rica that were chosen for variations in degree of human disturbance and management strategies. My objectives were to 1) determine if egg predation rates differ at the four sites, 2) determine the most destructive predators at each location, and 3) suggest management options to alleviate mammalian threats to turtle clutches on Playa Grande and Playa Cabuyal in Costa Rica. My results show that the beaches without a nest protection or predator control program had very high rates of predation. Invasive mammalian predators and mammalian predators associated with human disturbance were the most destructive at the four sites. I recommend that regulations regarding dogs and the take of eggs from the beach are enforced at Playa Cabuyal and that physical nest protection is rapidly implemented at Playa Grande. I also recommend that the National Park consider managing raccoon predation by removing problem individuals, but caution that they do so in a way that maintains the animals’ role in the ecosystem.</p>
165

Assistance dogs for military veterans with PTSD: a systematic review, meta-analysis, and meta-synthesis

Sarah Leighton (14035923) 02 November 2022 (has links)
<p>Psychiatric assistance dogs for military veterans with posttraumatic stress disorder (PTSD) currently make up over 19% of assistance dog partnerships globally. We conducted a systematic review of the literature relating to these partnerships, with specific aims to (1) summarize their characteristics, (2) evaluate the quality of existing evidence, and (3) summarize outcomes. A total of 432 records were independently screened (Cohen’s kappa=0.90). Of these, 41 articles (29 peer-reviewed publications and 12 unpublished dissertations) met inclusion criteria. Data extraction was conducted to address the research aims, including a meta-analysis (quantitative outcomes) and meta-synthesis (qualitative outcomes). All peer-reviewed publications on the topic of psychiatric assistance dogs for veterans with PTSD were published within the last five years. The majority of included articles were quantitative (53%), 41% were qualitative, and 6% employed mixed methods. Mean methodological rigor scores were 80% for peer reviewed articles and 71% for dissertations, where higher scores represent more rigorous methodology. Quantitative articles reported significant improvements in the domains of PTSD severity, mental health, and social health. Impacts on physical health and global quality of life appear inconclusive. Meta-analysis (9 articles) revealed that partnership with an assistance dog had a clinically meaningful, significant, and large effect on PTSD severity scores (<em>g</em>=−1.129; <em>p</em><0.0001). Qualitative meta-synthesis identified two third order constructs: (1) Impact on the individual: mental & physical health and (2) Impact beyond the individual: building relationships & connection. This synthesis of increasingly prevalent research on assistance dogs for veterans with PTSD provides support for the impact of this complementary and integrative health intervention on PTSD symptom severity, and signs of meaningful improvements in adjacent domains including mental and social health. Gaps between quantitative and qualitative findings, along with the need to report greater demographic detail, highlight key opportunities for future research.</p>
166

Effets d'une infection parasitaire sur la condition corporelle et les traits de comportement du crapet-soleil (Lepomis gibbosus)

Gradito, Maryane 08 1900 (has links)
Le parasitisme est de plus en plus considéré comme un facteur écologique pouvant créer des variations dans le comportement des individus. Toutefois, la direction de causalité entre le comportement et le parasitisme reste incertaine. Les infections expérimentales sont le plus souvent réalisées en laboratoire, limitant les inférences écologiques. À l’aide d’une infection expérimentale semi-naturelle, nous avons infecté avec succès des crapets-soleils (Lepomis gibbosus) dans un lac où ils ont été exposés à une variété de vers parasites (trématodes, cestodes), permettant d’examiner les effets de la co-infection naturelle chez les hôtes. Nous avons mesuré la témérité, l’exploration et l’activité avant et après l’infection expérimentale. En utilisant une approche bayésienne, nous avons trouvé que les traits de comportement initiaux exercent une forte influence sur la susceptibilité à l’infection : les poissons les plus téméraires et/ou les moins actifs au départ ont acquis une plus grande densité de points noirs (c.-à-d. points noirs visibles sous la peau, les nageoires et dans les muscles du poisson) et de cestodes lors de l’infection. Par ailleurs, nous avons montré que la condition corporelle est réduite par la densité de cestodes, suggérant la débilitation de l’hôte. La condition corporelle était corrélée positivement avec la distance parcourue, quel que soit le statut d’infection individuel. Nous avons également trouvé une relation négative entre la distance parcourue après l’infection et la densité de trématodes, suggérant que l’infection causant la maladie des points noirs diminue le niveau d’activité des hôtes. La témérité et l'exploration n'étaient pas affectées par la densité parasitaire ou la condition corporelle. Nous suggérons que la diminution de l’activité est causée par une réponse adaptative de l’hôte, visant à rediriger son énergie pour combattre l’infection. Sachant que les points noirs ont un cycle de vie complexe et que le crapet-soleil est un hôte intermédiaire, ce changement dans le comportement de l’hôte pourrait aider le parasite à compléter sa transmission aux oiseaux-hôtes piscivores en augmentant la prédation sur les poissons infectés. Bien que nous ne puissions confirmer la direction de causalité, nos résultats montrent qu’il existe un lien étroit entre le comportement et le parasitisme. Nous suggérons que deux mécanismes peuvent simultanément agir : le comportement initial des individus influence le risque d’infection, et l’infection peut créer de la variation au niveau de la plasticité comportementale des individus. / Parasitism is increasingly seen as an ecological factor that can create variations in individual behaviour. However, the direction of causality between behaviour and parasitism remains uncertain. Experimental infections are most often conducted in laboratories, limiting ecological inferences. Using a semi-natural experimental infection, we successfully infected pumpkinseed sunfish (Lepomis gibbosus) in a lake where they were exposed to various parasitic worms (trematodes, cestodes), allowing us to examine the effects of natural co-infection in hosts. We measured boldness, exploration, and activity before and after the experimental infection. Using a Bayesian approach, we found that initial behavioural traits strongly influence infection susceptibility: initially bolder and/or less active fish acquired a higher density of black spots (i.e., visible black spots under the skin, fins, and in the fish's muscles) and cestodes during the infection. Additionally, we found that body condition was reduced by cestode density, suggesting host debilitation. Body condition was positively correlated with distance swam, regardless of individual infection status. We also found a negative relationship between distance swam after infection and trematode density, suggesting that infection causing black spot disease decreases host activity levels. Boldness and exploration were not affected by parasite density or body condition. We suggest that a decrease in activity is caused by an adaptive host response to redirect its energy to combat the infection. However, since trematode parasites have a complex life cycle and pumpkinseed sunfish are intermediate hosts, decreases in activity levels following infection may make infected fish more susceptible to predation by piscivorous birds, which is needed for trematodes to complete their life cycles. While we cannot confirm the direction of causality, our results show a close link between behaviour and parasitism. We propose that two mechanisms may simultaneously operate: the initial behaviour of individuals influences their risk of infection, and infection can create variation in behavioural plasticity of individuals.
167

Soundscape dynamics in the social-ecological systems of Tierra del Fuego

Dante P Francomano (9738650) 14 December 2020 (has links)
<p>Human society is presently beset by an array of anthropogenic social-ecological crises that threaten the sustainability of the social-ecological systems that sustain our livelihoods. While research alone will not rectify these issues, it can help to answer key questions that must be addressed to develop effective solutions. To address such questions in a cohesive, compelling manner, social-ecological research can be bounded, structured, and distilled through innumerable organizing principles or theoretical frameworks. For this dissertation, I focused on the geographic region of Tierra del Fuego and sought to draw from the array of disciplines and methods that use sound as a lens for biological, ecological, and/or social inquiry. I also endeavored to consider various temporal, spatial, and organizational scales while investigating a selection of topics with a) specific importance in the social-ecological systems of Tierra del Fuego and b) general relevance to global social-ecological challenges. Chapter 1 provides an introduction to the dissertation, and Chapter 6 serves as a conclusion.</p><p><br></p><p> </p><p>The objective of Chapter 2, “Biogeographical and analytical implications of temporal variability in geographically diverse soundscapes”, was to provide some guidance to passive acoustic monitoring (PAM) practitioners on how to design appropriate temporal sampling schemes based on the temporal variability of the sounds one wishes to measure and the power and storage limitations of acoustic recorders. We first quantified the temporal variability of several soundscape measurements and compared that variability across sites and times of day. We also simulated a wide range of temporal sampling schemes in order to model their representativeness relative to continuous sampling.</p><p><br></p><p> </p><p>For Chapter 3, “Sentinels for sentinels: passive acoustic and camera trap monitoring of sensitive penguin populations”, we tested the utility of PAM to monitor behavior and abundance of Magellanic (<i>Spheniscus magellanicus</i>) and southern rockhopper penguins (<i>Eudyptes chrysocome</i>) at different spatial and temporal scales. We conducted <i>in situ</i> observations of the acoustic behavior of each species, and we compared acoustic metrics with penguin counts from narrowly focused camera traps and larger-extent observations of colony density. </p><p><br></p><p> </p><p>Chapter 4, “Acoustic monitoring shows invasive beavers (<i>Castor canadensis</i>) increase avian diversity in Tierra del Fuego”, is focused on impacts of the invasive North American beaver (<i>Castor canadensis</i>) on Fuegian bird communities. We sought to determine how bird communities might differ between intact riparian forests, beaver ponds, and beaver meadows created by pond drainage. We conducted PAM and classic avian point counts under each of these conditions across seasons to test for differences between impact conditions and to compare the two methodologies.</p><p><br></p><p> </p>For Chapter 5, “Human-nature connection and soundscape perception: insights from Tierra del Fuego, Argentina”, we evaluated the relationship between soundscape perception and nature relatedness by conducting surveys and soliciting responses to soundscape audio prompts. We also examined the potential for any demographic influences on nature relatedness or soundscape perception in the context of local social tensions.
168

TARGETED DELIVERY OF BONE ANABOLICS TO BONE FRACTURES FOR ACCELERATED HEALING

Jeffery J H Nielsen (8787002) 21 June 2022 (has links)
<div>Delayed fracture healing is a major health issue involved with aging. Therefore, strategies to improve the pace of repair and prevent non-union are needed in order to improve patient outcomes and lower healthcare costs. In order to accelerate bone fracture healing noninvasively, we sought to develop a drug delivery system that could safely and effectively be used to deliver therapeutics to the site of a bone fracture. We elected to pursue the promising strategy of using small-molecule drug conjugates that deliver therapeutics to bone in an attempt to increase the efficacy and safety of drugs for treating bone-related diseases.</div><div>This strategy also opened the door for new methods of administering drugs. Traditionally, administering bone anabolic agents to treat bone fractures has relied entirely on local surgical application. However, because it is so invasive, this method’s use and development has been limited. By conjugating bone anabolic agents to bone-homing molecules, bone fracture treatment can be performed through minimally invasive subcutaneous administration. The exposure of raw hydroxyapatite that occurs with a bone fracture allows these high-affinity molecules to chelate the calcium component of hydroxyapatite and localize primarily to the fracture site.</div><div>Many bone-homing molecules (such as bisphosphonates and tetracycline targeting) have been developed to treat osteoporosis. However, many of these molecules have toxicity associated with them. We have found that short oligopeptides of acidic amino acids can localize to bone fractures with high selectivity and with very low toxicity compared to bisphosphonates and tetracyclines.</div><div>We have also demonstrated that these molecules can be used to target peptides of all chemical classes: hydrophobic, neutral, cationic, anionic, short, and long. This ability is particularly useful because many bone anabolics are peptidic in nature. We have found that acidic oligopeptides have better persistence at the site of the fracture than bisphosphonate-targeted therapeutics. This method allows for a systemic administration of bone anabolics to treat bone fractures, which it achieves by accumulating the bone anabolic at the fracture site. It also opens the door for a new way of treating the prevalent afflictions of broken bones and the deaths associated with them.</div><div>We further developed this technology by using it to deliver anabolic peptides derived from growth factors, angiogenic agents, neuropeptides, and extracellular matrix fragments. We found several promising therapeutics that accelerated the healing of bone fractures by improving the mineralization of the callus and improving the overall strength. We optimized the performance of these molecules by improving their stability, targeting ligands, linkers, dose, and dosing frequency.</div><div>We also found that these therapeutics could be used to accelerate bone fracture repair even in the presence of severe comorbidities (such as diabetes and osteoporosis) that typically slow the repair process. We found that, unlike the currently approved therapeutic for fracture healing (BMP2), our therapeutics improved functionality and reduced pain in addition to strengthening the bone. These optimized targeted bone anabolics were not only effective at healing bone fractures but they also demonstrated that they could be used to speed up spinal fusion. Additionally, we demonstrated that acidic oligopeptides have potential to be used to treat other bone diseases with damaged bone.</div><div>With these targeted therapeutics, we no longer have to limit bone fracture healing to casts or invasive surgeries. Rather, we can apply these promising therapeutics that can be administered non-invasively to augment existing orthopedic practices. As these therapeutics move into clinical development, we anticipate that they will be able to reduce the immobilization time that is the source of so many of the deadly complications associated with bone fracture healing, particularly in the elderly.</div>

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