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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.
201

The Role of Previous Experience with Piscovory and Exposure to Fish Predators on Survival of Walleye (Sander vitreus) fingerlings

Echols, Richard Franklin 01 January 2009 (has links)
Walleye (Sander vitreus) culture for maintenance stocking in lakes has always been fraught with challenges. Their propensity to cannibalize at an early age and their reluctance to accept a prepared diet make the production of advanced fingerlings extremely costly. Hatchery reared walleye fingerlings are extremely vulnerable to predation when stocked into impoundments with established fish populations. This study was conducted to determine if fish culturists could increase walleye survival by exposing summer fingerlings to fish predators and/or providing experience with piscivory before being stocked for recreational angling. Tank studies were conducted to minimize environmental variation among experimental treatments and replicates. In 2005, 5 treatment groups were tested, including a group that was allowed to feed on zooplankton only, a group that was habituated to feed, a group that was exposed to a fish predator, a group that was given an opportunity to prey on fish, and a group that was exposed to a fish predator and given an opportunity to prey on fish. In 2006, the feed habituated group was lost to disease, but a feed habituated group that was given experience avoiding fish predators and opportunity to forage on fish prey and a feed habituated group that was given opportunity to forage on fish prey were added. Walleye fingerlings from the 5 treatment groups in 2005 were placed in tanks with cover and a 250 mm largemouth bass as a predator. Walleye survival was measured after 24 hours; no significant differences in survival were detected among treatment groups in 2005. In 2006, 10 walleye fingerlings from each of the 6 treatment groups were added to tanks fitted with a cedar reef for cover and two 250 mm largemouth bass. Fingerling walleye survival was highest in the feed habituated prey exposed group and the feed habituated predator and prey exposed group after 14 days; higher survival in these groups may have been due to their larger initial size. Pond studies were also conducted in 2005 and 2006 to evaluate differences in survival among treatment groups under conditions that more closely resemble environments into which fingerling walleye are stocked. Twelve 0.4-hectare ponds were prepared by placing 15 adult bluegill (~200 mm total length) and 5 adult largemouth bass (~300 mm total length) into each pond along with a 6.5 m cedar reef for cover. Survival of fingerling walleye in ponds was measured on days 3, 7, 15, 30, 60, 90, and 120 post-stocking. Pond and tank trials indicated no apparent post-stocking increase in survival for walleye fingerlings that were given prior exposure to predators or fish prey. Additionally, a multiple batch tagging / marking procedure was needed to separate walleye fingerling groups in ponds and tanks. Visible Implant Elastomer (VIE) tags and liquid nitrogen freeze brands were chosen and retention rates were determined for fingerling walleye, as little published information on retention rates for these techniques was available. VIE tags were lost steadily over time (41.67% retention at 270 days), while freeze branding showed much better retention (87.88% retention at 270 days).
202

An examination of the neurology behind the concept of the Self with consideration given to the effects of neurological impairment

Hirst, Ian January 1999 (has links)
The argument that I present in this thesis is that while the idea of the Self is an illusion, a myth which our brains create, it is one that is necessary for our survival. However, by understanding its neurological origins we are able to take advantage of it without being victims of egocentricity. My first chapter, Neurology of the Self, lays down the neurological foundations for our concept of the Self and goes on to argue that, while biology and neurology must remain the basis of our understanding, we need to transcend our purely scientific concepts in order to integrate them with art and spirituality. Our transcendental view, I argue, seeks to establish values that make life worth living for and are essential to our survival. I consider some possible implications, both real and imagined, of neurological impairment. The second chapter, Consciousness and the Self, considers the neurological and chemical basis for consciousness and develops the ways in which the imagined Self can be used to create a balanced life that is not highjacked by ego. In the third chapter, Human Nature and the Self, I continue to argue for a liberated view of the Self bearing in mind its neurological origin which itself is the creator of our received reality. Compassion, which Schopenhauer's philosophy argued for as the basis of morality, is shown to be facilitated by the concept of a centred Self which I apply to the subject of morality in the fourth chapter, Morality and the Self. .with the fifth chapter, Illusion and the Imagined Self. I come to the very heart of the argument to which tny considered research findings and previous chapters have lead, namely, that the illusion of the Self is neurologically created by our brains and that we do not have an unchanging Self which is other than the experiences and ideas from which our whole Being derives meaning. Nonetheless, this Self and other values we create are essential for our well being and should be cherished in themselves as being crucial for our healthy individual and collective survival. Furthermore, since we are now aware of the origin of our idea of the Self we can gain our freedom from a manipulating ego and become centred Selves able to creatively transcend and transform the limits of our neurologically given reality by being actively involved in the ongoing process of change. This is the subject of my sixth chapter, Spirituality and the Creative Self, and is endorsed in my concluding chapter which, neglecting a view which carefully avoids accepting absolutes that just might be falsified tomorrow, argues that the best values that we create today should be used as absolutes from which to derive principles for living and continuing to live which could, at least, lessen the threat to our survival.
203

Joint survival models : a Bayesian investigation of longitudinal volatility

Bester, Dirk W. January 2014 (has links)
In this thesis, we investigate joint models of longitudinal and time-to-event data. We extend the current literature by developing a model that assigns subject-specific variance to the longitudinal process and links this variance to the survival outcome. During development we provide the theoretical definition of the model and its properties, and explore the practical implications for estimating the parameters. We use Markov Chain Monte Carlo (MCMC) methods, and compare the different samplers used in similar models in the literature with our custom MCMC algorithm, written in C++. We use the Deviance Information Criterion to perform model comparisons, and we formalise suggestions from the literature to use posterior predictive model checking to construct a goodness-of-fit test for our model. We use the model on two real-world datasets to investigate claims relating to the importance of blood pressure volatility on stroke risk, and examine the consequences of ignoring measurement error. We amend our model to accommodate competing risk, time-dependent baseline hazard rates, and bivariate longitudinal processes - at which point we update our MCMC samplers and identify the issues. Finally, we use our code in a separate, but related, collaboration with other researchers to analyse repeated counts data.
204

Nesting Ecology, Survival, and Home Range of Wild Turkeys in an Agricultural Landscape

Delahunt, Kenneth Scott 01 May 2011 (has links)
Most research on Eastern wild turkeys (Meleagris gallopavo silvestris) has occurred in extensively forested habitats atypical of midwestern landscapes. I studied the ecology of female wild turkeys in a portion of southern Illinois consisting of an agricultural matrix interspersed with forest, and grassland cover types. I quantified causes of hen and nest mortality, nesting habitat variables, nesting rates, nest success, clutch and brood sizes, and incubation length. I also examined daily nest and weekly hen survival rates, and hen and brood home ranges and habitat selection. Sixty-four hens were radiomarked during 2008-10. Predation was the primary cause of nest mortality (80.5%) and hen mortality (100.0%). Coyotes (Canis latrans) were responsible for 40.3% of nest mortalities and 42.8% of hen mortalities, whereas bobcats (Lynx rufus) caused 42.8% of hen mortalities. Weekly survival rates were 98.7 and 98.6% for adult and juvenile hens, respectively. Seasonal survival rates for adult hens varied from 68.7% during breeding to 88.9% during winter. Most hens (98.5%) made a first nest attempt, 75.6% of hens attempted a second nest, and 8.0% of hens attempted a third nest. Mean clutch size was 12.4 ± 0.4 (SE throughout) during the first nesting attempt and 9.6 ± 0.6 during the second nesting attempt. The mean incubation length of successful nests was 31.1 ± 0.8 days. Mean nest success was 19.8%, producing 11.3 ± 3.3 poults/per
205

Survival and Capture Efficiency of River Otters in Southern Illinois

Rutter, Andrew U 01 December 2017 (has links)
River otter (Lontra canadensis) populations in Illinois have rebounded considerably after >80 years of harvest protection and a successful reintroduction program. However, few studies of river otter ecology exist in the Midwestern U.S. where river otter numbers have increased in recent decades. Capturing study animals safely and efficiently is a critical part of wildlife research, and difficulties associated with live capture of river otters have contributed to the dearth of research on the species. Furthermore, estimating survival rates and identifying causes of mortality are important in effectively managing river otters. To address these knowledge gaps, my objectives were determine survival rates and mortality causes for river otters in southern Illinois, and to measure injury rates of river otters captured using Comstock traps. During 2014-16, I captured 42 river otters 49 times at Crab Orchard National Wildlife Refuge (CONWR) in southern Illinois. Eight river otters (3 M, 5 F) were captured in foot-hold traps during 788 trap nights (1 capture/88 trap nights), and the remaining 34 (19 M, 15 F) were captured in Comstock traps during 2,540 trap nights (1 capture/64 trap nights). I detected no significant differences in efficiency or escape rate between the 2 trap types, but Comstock traps did have higher rates for both unavailability and non-target captures. Eleven of the 20 river otters inspected for injuries received some type of injury as a result of capture in a Comstock trap (55%). The most common injury was claw loss (45%), followed by tooth fracture (25%), and lacerations (10%). The ease of setting the Comstock traps and of releasing non-target captures made them a more appealing option than foot-hold traps; however, river otters have a propensity for doing permanent damage to their teeth when live captured in Comstock traps. My study provides information on the functionality and safety of a novel live capture method for river otters. Thirty-four (16 F, 18 M) river otters were successfully radio-marked and monitored for survival for a total of 8,235 radio-days (¯x days/river otter = 242.2 ± 20.6 [SE throughout]). Two river otters (2 M) died during the period of radio-telemetry monitoring: 1 was trapped during nuisance wildlife control activities at an adjacent fish hatchery, and the other died of unknown causes. Annual survival rates were 1.0 ± 0.00 (lower confidence bound = 0.83) and 0.85 ± 0.09 for females and males, respectively, and similar between sexes (χ_1^2 = 1.7, P = 0.19). Pooled-sex breeding season survival was 0.96 ± 0.04. Trapping was the primary source of mortality over the course of my study. After radio-telemetry ended, 2 river otters were harvested by recreational trappers, at 114 (1 M) and 120 (1 F) weeks post-capture, and 1 male was killed by a vehicle collision at 52 weeks post-capture. Primary mortality sources for river otters in southern Illinois are similar to those reported elsewhere (i.e., trapping and vehicle collisions). Although I found no significant difference in survival rates between sexes, the majority of otters that died during my study were male (4 M, 1 F). As river otters occupying CONWR are protected from harvest, males may be more likely to leave the confines of CONWR, thereby putting themselves at greater risk to recreational trapping mortality. My study provides useful demographic information for Illinois’ recently-recovered river otter population.
206

Avaliação da retenção de ionomero de vidro modificado por resina (Vitremer'TRADE MAKER') como selante oclusal, de acordo com o risco de carie dentaria / Avaliation of the retencion of ionomeric sealer modified by resin (Vitremer), as a oclusal sealer, according to cavities risk

Oliveira, Juliana Gobbo de 14 August 2018 (has links)
Orientador: Antonio Carlos Pereira / Dissertação (mestrado profissional) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-14T03:33:33Z (GMT). No. of bitstreams: 1 Oliveira_JulianaGobbode_M.pdf: 947660 bytes, checksum: 6fdaad170a78d94e585a32986b75b455 (MD5) Previous issue date: 2008 / Resumo: O objetivo do presente estudo foi avaliar, por meio de um modelo de análise de sobrevivência, a retenção do selante ionomérico modificado por resina (Vitremer®) aplicado sobre as superfícies oclusais dos primeiros molares permanentes de escolares de 6 a 8 anos de idade em Piracicaba, SP. Os escolares foram selecionados por meio de exame prévio e de acordo com o risco individual, por uma única examinadora, calibrada e seguindo as recomendações da OMS para a cárie dentária e adicionalmente, foi feita a inclusão de lesões iniciais ativas (LI). Foram incluídos os indivíduos que apresentaram ao menos dois primeiros molares permanentes hígidos, num total de 93 escolares provenientes de duas escolas municipais e alocados em dois grupos de acordo com o risco individual - Grupo (AS) - alto risco selante (n= 57) e aqueles com ceod e CPOD=0 pertenceram ao Grupo (BS) - baixo risco selante (n=52). A aplicação do selante ionomérico (Vitremer®) nas superfícies oclusais dos primeiros molares permanentes hígidos foi realizada em ambiente clínico e as avaliações e realizadas a cada seis meses por uma examinadora calibrada. Um modelo de análise de Sobrevivência (método de Kaplan-Meier) estimou as probabilidades de sobrevivência do selante na superfície oclusal (tempo para a perda total do selante). Aos 18 meses de acompanhamento os grupos AS e BS apresentaram 8 e 6 selantes com perda total do material, respectivamente, correspondendo a 4,1% de perda para os de alto risco e 3,1% para os de baixo risco. Em relação à perda parcial, observou-se aos 18 meses 11,7% e 9,3% para os grupos AS e BS, respectivamente. Não houve diferença entre os grupos quanto à sobrevivência do selante. Conclui-se que o selante ionomérico modificado por resina (Vitremer®) é satisfatório quanto à retenção, após 18 meses de avaliação e sugere-se estudos longitudinais mais extensos para averiguar essa retenção ao longo do tempo. / Abstract: The objective of the present study was to evaluate, by an analysis surviving model, the retencion of ionomeric sealer modified by resin (Vitremer), applied on oclusal surface of permanent molar teeth of children of age range 6-8 years on schools of Piracicaba city, SP. Children were selected by a previus exam and according to individual riscs, by only one evaluator, blinded and following the recomendations of WHO (World Health Organization) to cavities and additionally, included the initial cavities lesion. Patients who had at least two permanent molars with no cavities were included. Ninetythree students from two schools were recruted and divided according to individual riscs into the following groups: Group (HS) - high level sealer (n=57) and Group (LS) - low level sealer (n=52) whose teeth had "dmf" and DMFT = 0. The ionomeric sealer (Vitremer®) was applied in a clinical procedure on teeth with no cavities. Evaluation was done at every six months by an evaluator. An analysis surviving model (Kaplan-Meier method) evaluated the loss of the sealer from oclusal surface of the teeth. After 18 months groups HS and LS demonstrated 8 and 6 total loss of sealer, respecitvely. The percentage of lost were 4,1% to high level and 3,1% to low level. According to partial loss, after 18 months the percentage presented to HS was 11,7% and 9,3% to LS. There was no statistically significant difference between the two treatment groups from surviving sealer. The evaluation of the groups led to a conclusion that ionomeric sealer (Vitremer®) is very satisfatory on retencion after 18 months evaluation. Further research is required to determine the effectiviness and efficiency of sealer activity. / Mestrado / Odontologia em Saude Coletiva / Mestre Profissional em Odontologia em Saúde Coletiva
207

The causes and consequences of population declines of two boreal forest species:the case of the willow tit (<em>Parus montanus</em>) and the Siberian flying squirrel (<em>Pteromys volans</em>)

Lampila, S. (Satu) 08 April 2009 (has links)
Abstract I used individual-based capture-mark-recapture data and genetic markers to gain understanding of the demographic and genetic processes operating in small and declining populations of two different species, the willow tit Parus montanus and the Siberian flying squirrel Pteromys volans. Both species have declined in Finland and the flying squirrel has been considered to be vulnerable. The willow tit study was conducted in northern Finland, near city of Oulu. The population size in the studied area has on average been stable during the past decade. Adult survival in the willow tit was high and fairly stable and was positively correlated with recruitment. Adult survival has been the most influential vital rate to the population growth rate. Local recruitment and immigration have high variation, inducing variation in the population growth rate. Female willow tits use extrapair copulations to maximise offspring heterozygosity. Heterozygous individuals are supposedly of higher quality than homozygous ones. I found weak negative association between individual homozygosity and recruitment probability. The flying squirrel populations have declined during the past ten years. Furthermore, adult survival has declined in one of the populations, most likely due to habitat loss and fragmentation that decrease the adult survival and limit dispersal. The flying squirrel populations were studied in western Finland. The flying squirrel densities in the studied areas are the highest in Finland and therefore these areas have been regarded as favourable for the flying squirrel. My results question this view. Microsatellite analyses strengthen the view of populations doing poorly, because the heterozygosities in all the populations and particularly in the most isolated one were rather low. High FST values indicate low dispersal even between adjacent populations. Following work should investigate the spatial variation in individual performance and the dispersal processes in these populations. For the flying squirrel it is vital to determine the size and quality of the patches that can support flying squirrels and the ones that apparently can not. Present estimates of survival and genetic diversity can be used to reconstruct a meaningful PVA and projections for these populations.
208

Going Undrafted: Survival of Undrafted Free Agents and Seventh Round Draft Picks in the NFL

Smith, Trey 01 January 2018 (has links)
Over the years there have been a lot of undrafted free agents that have had successful careers in the NFL. The monopsony structure for rookies entering the NFL and the fact that undrafted free agents get to pick what team they play for suggests that there is an advantage in not getting picked in the draft. To explore this possibility, this paper compares the probabilities of remaining in the NFL for undrafted free agents and seventh round draft picks through logit regressions and survival analysis. In doing so, this paper describes the processes the NFL takes in order to find the most elite talent and how they distribute the talent throughout the whole league. The results find that undrafted free agents have a higher probability of exiting at the beginning of a career when compared with seventh round draft picks, but there is evidence that those probabilities start to converge later in careers. Additionally, there is evidence that there are NFL teams and position groups that do better and worse in retaining undrafted free agents, suggesting that there is a way to take advantage in going undrafted.
209

Inter-centre Variation in the Management of Kidney Transplant Recipients and Its Impact on Clinical Outcomes

Tsampalieros, Anne January 2018 (has links)
Introduction: There is an increasing number of Canadians living with end stage renal disease (ESRD). Kidney transplantation is currently the best treatment for ESRD but long-term outcomes remain suboptimal. Identifying factors associated with better outcomes may lead to interventions or practice change that could improve patient survival or quality of life. The objectives of this thesis were to: i) systematically review the literature to examine centre variation in kidney transplantation outcomes and identify centre and provider level factors that may contribute to variation in outcomes; ii) describe differences that may exist at the patient, centre and provider level at the time of kidney transplantation across the six transplant centres in Ontario, Canada; iii) examine variation in graft and patient survival rates across transplant centres in Ontario; and iv) examine whether patient, centre and provider level characteristics contribute to variation in graft and survival rates across transplant centres. Methods: The first objective of this thesis was met by conducting a systematic review of the literature according to a predefined protocol. The last three objectives of the thesis were met by conducting a population based retrospective cohort study using administrative data from Ontario. Differences at the patient, centre and provider level were described at the time of kidney transplantation. Outcomes of interest included total graft loss; graft loss with follow-up censored at death; death with graft function; and total mortality. All outcomes were assessed at one year post transplantation and at the end of study follow up. Cox proportional hazards regression was used to obtain hazard ratios (HR) for each centre relative to the average across all centres. The independent effect of centre volume and provider characteristics on outcomes was also examined. Results: The systematic review identified 24 eligible studies. Outcomes included graft survival (n=24) and patient survival (n=9). The main characteristics evaluated were centre volume (n=17) and provider volume (n=2). Centre variation in graft survival was described in 80% (12/15) of studies, while less than half of studies (8/17) found a significant association between volume and graft survival. The population based retrospective cohort included 5092 adults (≥18 years) who received a primary solitary kidney transplant across 6 transplant centres in Ontario between January 1st 2000 and December 31st 2013. Variation in patient, centre and provider level factors existed across centres at the time of transplantation. At the end of study follow-up, case-mix adjusted HRs for total graft loss ranged from 0.84 (95% CI 0.53-1.33) to 1.16 (95% CI 1.00-1.34) across centres (p-value for between centre variation 0.46). After adjusting for centre and provider factors, differences across centres persisted. Centre volume, provider experience and provider type were not independently associated with either short or long-term outcomes (all p>0.05) with the exception of graft loss with follow-up censored at death. Discussion: This thesis suggests that there is variation in clinical outcomes across transplant centres in Ontario which is not explained by patient factors, centre volume or provider characteristics at the time of transplantation. Additionally centre volume, provider type and experience were not independently associated with outcomes. Future prospective studies with a larger sample size of transplant centres that examine follow-up care after discharge from hospital (e.g. frequency of visits) are required to better understand this phenomenon.
210

Matrix metalloproteinase-2 (MMP-2) and -9 (MMP-9) in hematological malignancies

Kuittinen, O. (Outi) 14 February 2003 (has links)
Abstract Gelatinases (MMP-2 and MMP-9) play a key role during invasion and metastazising of malignant cells and they have been shown to be associated to invasive phenotype and poor prognosis in several solid tumours. However little is known about their role in hematological malignancies. In the present work, gelatinase expression and its clinicopathological correlations were studied with immunohistochemical staining in 10 cases representing normal bone marrow aspirate smears, 123 cases representing diagnostic bone marrow samples of patients with different leukaemias (35 AML, 7 CLL, 6 CML, 75 ALL), 67 diagnostic paraffin-embedded lymph node biopsies from patients with Hodgkin's lymphoma and 57 biopsies from patients with non-Hodgkin's lymphomas. The lymphoma samples were also stained with factor VIII antibody to evaluate the extent of new vessel formation and the non-Hodgkin's lymphoma cases also with tissue inhibitor of metalloproteinases -1 (TIMP-1) antibody. CLL did not express either of the MMP enzymes, while CML in the chronic phase expressed strongly both of the enzymes. In ALL, gelatinase expression was weak and detectable in pediatric cases in only 12.7% and in the adults in 65% of the cases. In adult ALL, MMP-2 expression correlated strongly with an extramedullary and invasive pattern of disease presentation. In AML MMP-2 positivity had markedly favorable prognostic and predictive power. In lymphoma studies, no correlations could be detected between gelatinase expression and the clinical parameters of invasion. MMP-9 positivity was related to the presence of B symptoms, which difference was statistically significant in Hodgkin's lymphoma. In Hodgkin's lymphoma, strong MMP-9 expression also implicated decreased neovascularization. In both lymphoma types, strong MMP-9 expression correlated with unfavorable prognosis, which difference was statistically significant in non-Hodgkin's lymphomas and remained as a tendency in Hodgkin's lymphoma. MMP-2 had statistically significant association with a favorable prognosis in Hodgkin's lymphoma. Combination of the results of both stainings further increased prognostic power. All together these findings implicate that gelatinases could be used as prognostic tools in AML and lymphomas albeit this needs to be verified in larger materials.

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