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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.
111

Tick size regulation and the liquidity of UK venues: Three market microstructure essays

Nuzzo, Maria Francesca 23 October 2020 (has links)
This dissertation contributes to the research in the applied market micro-structure field, aiming to investigate the impact of a specific article of the MiFID II enforced on the 3rd of January 2018: the so-called tick size regime. It is constituted by three papers that see in the market regulators and policy-makers their optimal target. The first paper evaluates the consequences of the new regulation on UK minor venues in terms of liquidity and price discovery and highlights minor unintended consequences in the implementation of the new grid. The second paper builds on these conclusions and promotes an alternative to ESMA grid, a recalibration of the tick size that might lead to a greater orderliness of UK order books. Thethirdpaperendogenouslyinvestigatesthebehaviourofthemarketparticipants in the time frame around the MiFID II enforcement, simulating liquidity breakdowns thus providing the regulators with new simple metrics to detect and monitor abnormal market participants interactions.
112

Effects of Habitat, Density, and Climate on Moose and Winter Tick Ecology in the northeastern U.S.

Berube, Juliana 25 March 2024 (has links) (PDF)
Over the past several decades, moose (Alces alces) populations in New England have been in decline due to winter tick (Dermacentor albipictus) parasitism. Winter ticks have been known to infest moose, with over 90,000 ticks being recorded on a single moose. These severe infestations, known as epizootics, are associated with high annual calf mortality rates (> 50%) and reductions in annual productivity (adult calving and twinning rates < 60% and 5%, respectively). Given this, it is increasingly important to effectively monitor moose and winter ticks to address consistent population decline of moose due to winter tick epizootics. The objectives of this work were to measure off-host winter tick abundance and associated environmental variables and compare off-host tick abundance in relation to moose abundance. To assess moose and winter tick abundance, I used a combination of camera traps and winter tick sampling. I set an array of 60 cameras across central-western Massachusetts, which contribute data to the Northeast Wildlife Monitoring Network. I used a plot-based sampling strategy that is effective for heterogenous habitat types to sample winter ticks at sites in western and central Massachusetts as well as the White Mountain National Forest and Umbagog National Wildlife Refuge in New Hampshire. The Penobscot Nation developed the tick sampling approach and contributed additional winter tick data from their sovereign trust lands in Maine. I used N-mixture models to generate estimates of tick abundance for each of the three study areas. Results from this study can inform monitoring strategies for ticks, predict epizootic severity, and develop tools to mitigate threats to moose. This is important for managers looking to prevent further declines in moose populations due to winter ticks and tribes seeking to maintain populations for sustenance.
113

Investigations into the vector competency of arthropods for two Ehrlichias: Ehrlichia risticii and Cowdria rumantium

Hahn, Nina 20 September 2005 (has links)
Three studies relating to the vector competency of several species of ticks and <i>Simulium</i> spp. (blackflies) for <i>Ehrlichia risticii</i>, causative agent of Potomac horse fever (PHF) and <i>Amblyomma variegatum</i> for <i>Cowdria ruminantium</i>, causative agent of heartwater, are described. <i>Dermacentor variabilis, Rhipicephalus sanguineus, Amblyomma americanum and Ixodes scapularis</i> ticks were investigated for their ability to acquire and transmit PHF. Larval and nymphal ticks were exposed to <i>E. risticii</i> by feeding on mice inoculated with the organism. Molted exposed ticks were then allowed to feed on susceptible ponies or mice and were examined by light and electron microscopy. No evidence of transmission, either clinically or by seroconversion in mice or ponies was observed. Blackflies (<i>Simulium</i> spp.) were trapped in an area endemic for PHF and inoculated into mice in an attempt to demonstrate <i>I. risticii</i>. No evidence of seroconversion by mice to <i>E. risticii</i> was observed. Two laboratory colonies of <i>Amblyomma variegatum</i> ticks were investigated for their ability to acquire and transmit C. <i>ruminantium</i> and was febrile. Nymphs from both laboratory groups were simultaneously fed on a goat that had been infected with C. <i>ruminantium</i> and was febrile. Engorged nymphs from both groups were replete from feeding on three consecutive days. Nymphs from both groups were then incubated under identical conditions until molting. / Ph. D.
114

The effects of wildflower plots and diverse landscapes on ecosystem services, bee communities, and on-farm tick abundance

McCullough, Christopher T. 03 June 2020 (has links)
Conservation of natural habitats and planting wildflower plots are two commonly promoted tactics to enhance pollination services and biological control of crop pests, which are ecosystem services that can improve agricultural outputs. There are several programs at various levels of government in the United States that landowners can use to defray the costs of implementing these conservation strategies. Studies of European Agricultural Environmental Schemes have shown these tactics to have positive outcomes for crop production. However, real-world applications of cost-sharing programs have not been evaluated in the United States on pollination services and biological control. Furthermore, these tactics may inadvertently perform ecosystem disservices, like increasing crop pests or creating habitat for disease vectors. In this study, we evaluated the effects of natural habit and wildflower plots on biological control, pollination services, bee communities, and tick populations in Eastern Virginia and Maryland. This research was conducted on 22 farms. 10 of these farms had wildflower plots that were designed by Natural Resource Conservation Service personnel, and implemented by cooperating farmers. Collards, strawberries, tomatoes, and squash were used as model systems. We measured pest density, sentinel egg predation, crop damage, seed pollination, biomass production, marketable crop yield, sampled the bee community, and recorded tick abundance in wildflower plots. Many of the measures of biological control and pollination services had idiosyncratic results in regards to the wildflower plots and natural habit in the landscape. However, the proportion of high quality yield for all four crops increased with increasing natural habitat in the landscape. Bee communities between sites with and without wildflower plots were not different. Bee abundance did increase at wildflower sites when natural habitat comprised a certain proportion of the habitat around the site. Ticks were sampled from wildflower plantings, but not in greater abundance compared to field margins. In this study, the effects of wildflower plots were overshadowed by the landscape effects of natural habitat. Government personnel that oversee these programs may need to consider the surrounding landscape when helping implement on-farm conservation measure like wildflower plots. Such measures, do not perform an ecosystem disservice in regards to ticks. / Doctor of Philosophy / Conservation of natural habitats and planting wildflower plots are two strategies to enhance pollination services and biological control of crop pests. These two ecosystem services are of needed to improve agricultural production without further damaging the environment. There are several programs at various levels of government in the United States that landowners can use to subsidize the costs of implementing these strategies. European studies have shown these government programs to be successful. However, these programs have not been evaluated in the United States on their ability to enhance pollination services and biological control. Furthermore, studies investigating potential ecosystem disservices these strategies. In this study, we evaluated the effects of natural habit and wildflower plots on biological control, pollination services, bee communities, and tick populations in Eastern Virginia and Maryland. This research was conducted on 22 farms. 10 of these farms had wildflower plots that were designed by Natural Resource Conservation Service personnel, and implemented by cooperating farmers. Collards, strawberries, tomatoes, and squash were used as model systems. We measured pest density, egg predation, crop damage, seed pollination, and yield. We also sampled the bee community, and recorded tick abundance in wildflower plots. There were no consistent trends for many measures of biological control and pollination services in response to the wildflower plots and natural habit. However, the proportion of high quality yield for all four crops increased with increasing natural habitat in the landscape. Bee communities between sites with and without wildflower plots were not different. Bee abundance did increase at wildflower sites when natural habitat comprised a certain proportion of the habitat around the site. Ticks were sampled from wildflower plantings, but not in greater abundance compared to field margins. In this study, the effects of wildflower plots were overshadowed by the landscape effects of natural habitat. Government personnel that oversee these programs may need to consider the surrounding landscape when helping implement on-farm conservation measure like wildflower plots. Such measures, do not perform an ecosystem disservice in regards to ticks.
115

Znalosti žáků vybrané základní školy o nemocech přenášených klíšťaty / Students' knowledge of upper primary school about diseases transmitted by ticks

Michálková, Pavla January 2015 (has links)
The main research problem concerns the characteristics of tick-borne disease and determine the quantity and quality of information that students get in health education and biology of these diseases. The theoretical part deals with the history, etiology, clinical features, diagnosis, treatment and prevention of tick-borne encephalitis and Lyme disease. It also discusses the general problems of tick and other diseases that ticks carry and cause. Also is mentioned the inclusion of tick-borne diseases in the educational program. The practical part is devoted to the awareness of upper primary school students and changes in their knowledge about the issue during their elementary education. The aim of this thesis is to determine how the students are informed about diseases transmitted by ticks, especially about Lyme disease and tick-borne encephalitis. This method is used questionnaire, which includes questions regarding this issue. Although the results of the research show a certain degree of knowledge of students at upper primary school, especially in some classes is unsatisfactory. Based on research, there is provided a recommendation for pedagogical practices. KEYWORDS: tick, tick-borne encephalitis, Lyme disease, knowledge, disease, upper primary school
116

Carrapatos de Animais Silvestres e Dom?sticos no Pantanal sul Mato-grossense (Sub-regi?o da Nhecol?ndia): Esp?cies, Hospedeiros e Infesta??es em ?reas de Manejos Diferentes / Ticks of Wild and Domestic animals of Pantanal Wetlands, Matogrosso-do-sul State (Nhecol?ndia sub-region): Species, Hosts and Infestations in Areas With Different Managements.

Can?ado, Paulo Henrique Duarte 29 February 2008 (has links)
Made available in DSpace on 2016-04-28T20:16:26Z (GMT). No. of bitstreams: 1 2008- Paulo Henrique Duarte.pdf: 2250009 bytes, checksum: dd3eac04ae943ebe159aceec0bddbead (MD5) Previous issue date: 2008-02-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This research is a study about the tick fauna of Pantanal wetlands, MS, Brazil. Evaluation of cattle-raising on ticks populations, a detailed study on tick feeding on feral pigs and a list of ticks witch are reported in the study area are included. The cattle-raising impact was evaluated by trapping free-living ticks using a CO2 tick-trap. The traps were distributed in two areas: protected area, and the Nhumirim Ranch. Both areas are contiguous and locate at sub-region of Nhecol?ndia (18?59 S and 56?39 W), Pantanal of Mato Grosso do Sul state, Brazil. In each area, four habitat types were selected: cerrado (tropical savanna), forest patches, lakes and soda lakes. The last two are temporary lagoons of fresh and salted water, respectively. A total of 980 nymphs, 613 adults and 13 larvae of ticks of the genus Amblyomma were collected in 256 hours of collection. In a pen of calves infested by Ornithodoros rostratus 114 specimens were collected in just two hours including larvae, nymphs and adults. Adults of A. cajennense and A. parvum were more abundant in the savanna at Nhumirim Ranch, but did not differ among habitat types at protected area. There was a tendency of having more nymphs in Nhumirim Ranch than in protected area. The second conduced experiment was the comparison of the tick fauna of feral pigs at dry and wet seasons. A total of 44 feral pigs were examined and the species found were A. cajennense, A. parvum e O. rostratus. More adult ticks were collected in the dry season. Ecological and epidemiological aspects were discussed. Feral pigs are introduced specie and the role of this mammal on amplifying Amblyomma cajennense is clear. O. rostratus seems to be accidental parasite of feral pigs. The last part is a commented list of species including collected data and scientific literature. Up to day 18 tick s specie are reported on Pantanal wetlands including Argasidae (two) and Ixodidae (16) tick s species. The main genus was Amblyomma and the same species founded on wildlife are present on domestic animals and humans. / A presente tese ? um estudo sobre o impacto da bovinocultura extensiva sobre a popula??o de carrapatos, e um levantamento da fauna de carrapatos da regi?o com um estudo detalhado sobre a ixodofauna do porco monteiro. Para o estudo de impacto da bovinocultura, foram utilizadas armadilhas de CO2, distribu?das em duas ?reas: Reserva Biol?gica e Fazenda Nhumirim. Ambas as ?reas s?o contiguas e est?o localizadas na sub-regi?o da Nhecol?ndia (18?59 S e 56?39 W). Em cada ?rea quatro tipos de habitat foram selecionados: cerrado, mata, baia e salina. Os dois ?ltimos s?o lagoas tempor?rias de ?gua doce e salobra, respectivamente. Na totalidade foram coletadas 980 ninfas, 613 adultos e 13 larvas de carrapatos do g?nero Amblyomma em 256 horas de coletas. Em um bezerreiro infestado por Ornithodoros rostratus, 114 exemplares, dentre larvas ninfas e adultos foram coletados em apenas duas horas de atividade. Adultos de A. cajennense e A. parvum foram mais abundantes no cerrado da Fazenda, mas n?o diferiram entre os tipos de habitat na Reserva Biol?gica. Existe uma tend?ncia para uma maior abund?ncia de ninfas de Amblyomma na Fazenda do que na Reserva Biol?gica. O outro estudo realizado comparou a fauna de carrapatos adultos dos porcos monteiros entre as esta??es, cheia e seca. Os carrapatos encontrados foram A. cajennense, A. parvum e O. rostratus. E foram encontrados mais carrapatos adultos na seca que na cheia, foi discutida a import?ncia eco-epidemiol?gica destas rela??es parasit?rias, principalmente em fun??o do Porco monteiro ser uma esp?cie introduzida na regi?o. O ?ltimo cap?tulo apresenta uma lista comentada que reuniu os dados coletados pelo autor bem como resultados publicados na literatura cient?fica. Nos dias de hoje, existe registro de 18 esp?cies de carrapatos inclu?do as fam?lias Argasidae (2) e Ixodidae (16). O g?nero mais comum foi Amblyomma e as mesmas esp?cies de carrapatos foram comuns para animais selvagens, dom?sticos e para o homem, o que constitui uma rede complexa e din?mica de hospedeiros e parasitas.
117

Vliv klíštěcích slin na replikaci viru klíšťové encefalitidy v myších makrofázích. Úloha interferonu-\recke{beta} a oxidu dusnatého.

BERÁNKOVÁ, Zuzana January 2017 (has links)
The aim of this study was to characterize the replication of tick borne encephalitis virus in mouse macrophages and investigate the influence of tick saliva derived from Ixodes ricinus on the viral replication. Moreover, the effect of interferon (the member of type I interferons) and nitric oxide on virus replication was studied.
118

Vliv infekce klíšťat Ixodes ricinus virem klíšťové encefalitidy na jejich aktivitu / Effect of infection with the tick-borne encephalitis virus on Ixodes ricinus tick activity

VÝLETOVÁ, Eva January 2018 (has links)
The aim of this study was to examine the effect of tick infection with tick-borne encephalitis virus on its behaviour and development. The effect of infection on feeding performance, metamorphosis, locomotion or phototaxis was analysed. Despite the fact that we were not able to demonstrate any significant effect of infection on tick behaviour, the obtained results contribute to understanding transmission dynamics of the virus during tick life cycle including co-feeding and transovarial transmission.
119

Klíšťová encefalitida v Libereckém kraji v letech 2001-2016 / Tick-borne encephalitis in Liberec Region during 2001-2016.

CHMELAŘOVÁ, Šárka January 2018 (has links)
The presented thesis is focused on a comprehensive evaluation of situation related to the Tick-borne encephalitis on the territory of the Liberec Region in years 2001 2016. One of the main aims was to process the results of a demographic analysis of the Tick-borne encephalitis cases. These cases have been reported for 16 years within the so-called Tick-borne encephalitis surveillance to the system called EPIDAT by the Regional public health authority of the Liberec Region. Thank these analyzed data it was possible to create maps which illustrate particular focuses of the Tick-borne encephalitis in the Liberec Region and which graphically draw attention to locations threatened with infection. The KAP questionnaire study was held in a chosen Tick-borne encephalitis focus in order to improve a prevention of the Tick-borne encephalitis in the Region. This study was focused on knowledge, attitudes, opinions and practice of locals related to an occurrence of ticks and also of the Tick-borne encephalitis transmitted by them. Together with data gathering was held the distribution of the informative leaflets and also edification in this issue by a discussion about respondent´s questions. The collected data were processed by a descriptive method and also were detailed to a statistics testing. Due to an amount of analyzed information, this testing did not bring any statistic important results in most of the questions. The contribution of this thesis is especially the processed data of the Tick-borne encephalitis for those mentioned 16 years. These data could be useful for example for arguments of the public health authorities in case of discussion related to the Tick-borne encephalitis issue. The questionnaire study pointed out a problem which could cause a failure of people prevention. This problem means less of interest in health issues from their side. The question is how to learn population to perceive the risk of this disease when the half of the respondents do not feel threatened by the Tick-borne encephalitis? This fact is not certainly a problem only in the prevention of infectious diseases.
120

Atividade carrapaticida do timol sobre larvas e ninfas de Amblyomma cajennense (Acari, Ixodidae) fêmeas ingurgitadas e ovos de Rhipicephalus (Boophilus) microplus (Acari, Ixodidae)

Silva, Andressa Mendes Ribeiro e 24 January 2011 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-09-12T14:45:10Z No. of bitstreams: 1 andressamendesribeiroesilva.pdf: 2026948 bytes, checksum: 19277115bed655135017cdb6e87636f9 (MD5) / Approved for entry into archive by Diamantino Mayra (mayra.diamantino@ufjf.edu.br) on 2016-09-13T12:56:39Z (GMT) No. of bitstreams: 1 andressamendesribeiroesilva.pdf: 2026948 bytes, checksum: 19277115bed655135017cdb6e87636f9 (MD5) / Made available in DSpace on 2016-09-13T12:56:39Z (GMT). No. of bitstreams: 1 andressamendesribeiroesilva.pdf: 2026948 bytes, checksum: 19277115bed655135017cdb6e87636f9 (MD5) Previous issue date: 2011-01-24 / Dentre as várias espécies de ixodídeos existentes na região neotropical, Rhipicephalus (Boophilus) microplus e Amblyomma cajennense são duas das que despertam maior interesse econômico e em saúde pública, ocasionando perdas na produção animal e atuando como vetores de agentes patogênicos. A utilização de carrapaticidas químicos sintéticos é o método predominante no controle destes artrópodes, entretanto, o uso indiscriminado tem resultado em sérios problemas, como a pressão de seleção de carrapatos resistentes, risco de intoxicação de animais e do homem. Uma alternativa a estes métodos tem sido o uso de substâncias de origem vegetal de pouca ou nenhuma toxidez para animais e humanos. Assim, o presente trabalho teve como objetivo avaliar a atividade carrapaticida do timol em diferentes concentrações sobre larvas e ninfas de A. cajennense e fêmeas ingurgitadas e ovos de R. microplus. O estudo foi desenvolvido no Laboratório Avançado de Zoologia da Universidade Federal de Juiz de Fora, Minas Gerais, Brasil. No primeiro estudo (subdividido em dois experimentos) foi avaliada a influência de diferentes concentrações de timol (1,0%, 1,5%, e 2,0%) sobre os parâmetros biológicos da fase não parasitária de fêmeas ingurgitadas de R. microplus e também sua atividade sobre ovos deste carrapato. Os seguintes parâmetros biológicos foram observados: peso inicial (mg); peso de massa de ovos (mg); período de pré-postura (dias), período de postura (dias), período de sobrevivência (dias); percentual de eclosão de larvas; índice de produção de ovos (IPO), índice nutricional (IN) e eficácia do tratamento. No primeiro experimento os parâmetros peso da fêmea antes da postura e período de pré-postura não apresentaram diferenças significativas (p>0.05) entre os grupos. As diferentes concentrações de timol causaram alterações nos parâmetros peso da massa de ovos, período de postura, período de sobrevivência, percentual de eclosão de larvas, IPO, e IN, sendo constatadas diferenças altamente significativas entre os grupos tratados e o controle (p<0.01). A eficácia de controle foi superior a 95% em todos os tratamentos, chegando a 99% na concentração de 2,0%. O percentual de eclosão de larvas não foi afetado em nenhum dos tratamentos (p>0.05). No segundo estudo foi avaliado o potencial carrapaticida do timol sobre larvas não ingurgitadas e ingurgitadas e ninfas ingurgitadas de A. cajennense. Os valores referentes à mortalidade de larvas não ingurgitadas foram de 18,2%, 51,8%, 97,6%, 93,5%, 94,5%, e para ninfas ingurgitadas foi de 26,0%, 92,2%; 100,0%, 100,0%, 100,0% nas concentrações de 0,25%; 0,5%; 1,0%; 1,5% e 2,0%, respectivamente. No teste com larvas ingurgitadas a mortalidade foi de 100,0% em todos os tratamentos. Os resultados encontrados no estudo demonstram que o timol possui ação carrapaticida, interferindo na maioria dos parâmetros analisados para R. microplus, apresentando também atividade acaricida sobre imaturos de A. cajennense, sendo larvas e ninfas ingurgitadas mais susceptíveis do que larvas não ingurgitadas. / Among the various species of Ixodidae existing in the Neotropics, Rhipicephalus (Boophilus) microplus and Amblyomma cajennense are two of the ones that arouse more economic and public health interest, causing losses in animal production and acting as pathogens vectors. The use of synthetic chemical acaricide is the predominant method in controlling these arthropods; however, the indiscriminate use has resulted in serious problems such as the pressure on the selection for resistant ticks and the risk of animal and man toxicity. An alternative to this method has been the use of plant origin substances with little or no toxicity to animals and humans. The fore, this study aimed to evaluate the acaricide activity of thymol in different concentrations on larvae and nymphs of A. cajennense and engorged females and eggs of R. microplus. The study was conducted in the Advanced Laboratory of Zoology at the Federal University of Juiz de Fora, Minas Gerais, Brazil. In the first study (divided into two experiments) it was evaluated the influence of different concentrations of thymol (1.0%, 1.5% and 2.0%) on the biological parameters of the non-parasitic phase of R. microplus engorged females and also its activity on the eggs of this tick. The following biological parameters were observed: initial weight (mg), eggs weight mass (mg), pre-oviposition (days), oviposition period (days), survival period (days), percentage of hatching; egg production index (IPO), nutritional index (NI) and treatment efficacy. In the first experiment, the parameters weight of the female before oviposition and pre-oviposition presented no significant differences (p> 0.05) between groups. The different concentrations of Thymol caused changes in the parameters eggs weight mass, oviposition period, survival period, percentage of hatching, IPO, and IN, having found highly significant differences between the treated and control groups (p <0.01) . Control efficacy was greater than 95% in all treatments, reaching 99% at 2.0%. The percentage of hatching was not affected in any treatment (p> 0.05). In the second study it was evaluated the acaricide potential of Thymol on not engorged and engorged larvae and engorged nymphs of A. cajennense. The values concerning the mortality of not engorged larvae were 18.2%, 51.8%, 97.6%, 93.5%, 94.5%, and for engorged nymphs they were 26.0%, 92.2 % 100.0% 100.0% 100.0% at concentrations of 0.25%, 0.5%, 1.0%, 1.5% and 2.0% respectively. In tests with engorged larvae the mortality was 100.0% in all treatments. The results found in this study demonstrate that Thymol has an acaricide action, interfering in the majority of the analyzed parameters for R. microplus, also showing acaricidal activity on immature A. cajennense, being larvae and engorged nymphs more susceptible than not engorged ones.

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