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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.
101

An integrative chronobiological-cognitive approach to seasonal affective disorder

Rough, Jennifer Nicole 01 January 2016 (has links)
ABSTRACT Seasonal affective disorder (SAD) is characterized by annual recurrence of clinical depression in the fall and winter months. The importance of SAD as a public health problem is underscored by its high prevalence (an estimated 5%) and by the large amount of time individuals with SAD are impaired (on average, 5 months each year). The specific cause of SAD remains unknown; however, researchers have identified possible chronobiological and psychological vulnerabilities to SAD. The study aimed to clarify psychological and chronobiological correlates of SAD in the first test of an integrative model of SAD. The project used a longitudinal design to test the respective contributions of the chronobiological and cognitive vulnerabilities on winter depression severity in 31 SAD patients and 33 never-depressed controls at sites in Burlington, VT and Pittsburgh, PA. The measures selected for the cognitive vulnerability were established measures of vulnerability to nonseasonal depression with empirical support for their relevance to SAD: brooding rumination, dysfunctional attitudes, cognitive reactivity to an induced sad mood, and season-specific cognitions. The chronobiological vulnerability was measured as Phase Angle Difference (PAD) and deviation from PAD of 6 hours. All measures were completed once in the summer, when the SAD patients were remitted, and once in the winter, when patients were clinically depressed. Patients were distinguished from controls on most cognitive vulnerability measures (brooding, as well as rumination, dysfunctional attitudes, and seasonal beliefs). SAD patients exhibited shorter PAD than controls, but did not exhibit greater deviation from PAD-6. Results provide further support for specific cognitive, but not chronobiological, vulnerabilities in prediction of SAD. Limitations of the current sample are discussed. Results hold implications for future SAD research bridging the chronobiological and psychological disciplines with the ultimate aim of improved understanding, assessment, treatment, and prevention of SAD.
102

The atmospheric nitrogen budget over the South African Highveld

Ferguson, Kirsten Sheena 15 March 2010 (has links)
Molecular nitrogen is a highly abundant element in the atmosphere; it is stable and not very reactive. Anthropogenic activities have caused greater concentrations of nitrogen-containing compounds that are highly reactive and ultimately toxic. Reactive nitrogen concentrations have become a growing concern on the South African Highveld, with satellite images indicating very high nitrogen dioxide concentrations in the region. This study investigates the nitrogen budget on the Highveld through the analysis of the nitrogen species emitted into the atmosphere on a temporal scale as well as the atmospheric conversion, transport and removal of these species. Data was collected at Elandsfontein monitoring site, which is centrally located on the industrialised Highveld. The formation and interaction of nitric oxide (NO), nitrogen dioxide (NO2), and nitrate (NO3) are a major focus in the study. NOx concentrations are higher in winter (6.5 to 8.5 μg.m-3) as a result of stable atmospheric conditions. NO3 concentrations also peak during winter (3.5 to 5.5 μg.m-3), with a distinct biomass burning peak during July and August. Diurnally, NOx concentrations indicate a tall-stack industrial source, with concentrations peaking at midday. NO3 concentrations are higher at night and lower during the day, as during the day the NO3 radical is rapidly photolysed and nitrates cannot be produced. Case studies indicate that the conversion rate of NO to NO2 is highly variable as a result of varying atmospheric factors. These rates range from 11% to 59% per hour. Rates of dry deposition of NO, NO2 and NO3 are generally higher during winter as a result of higher concentrations and increased atmospheric stability, which prevents transport out of the region. Nitrogen is predominantly deposited as NO2 throughout the year, except during spring when NO3 deposition dominates. The total amount of nitrogen deposited to the Mpumalanga Highveld region is in the range of 6.7 to 13.1 kg ha-1 yr-1, which is well below the stipulated critical load value. Such deposition therefore does not pose significant threats to the natural environment on the Highveld. Between 4% and 14% of the total emitted nitrogen on the Highveld is deposited to the surface via wet and dry deposition. The remainder stays in the atmosphere and is advected out of the region.
103

Identificação de novos alérgenos de pólen do cajueiro (Anacardium occidentale L.) para auxílio no diagnóstico e futura otimização do tratamento / Identification of novel allergens of cashew pollen

Figo, Daniele Danella 28 June 2017 (has links)
A polinose é uma rinite alérgica sazonal que acontece pela sensibilização por pólens. Possui periodicidade anual, repetindo-se os sintomas sempre na mesma época do ano. Clinicamente, é caracterizada por rinoconjuntivite e/ou asma brônquica. A imunoterapia alérgeno-específica é o único tratamento capaz de modificar a evolução natural da doença, porém, depende fundamentalmente da correta identificação do alérgeno responsável. Diante disso e do número de pacientes que procuram o Ambulatório de Alergia da Universidade de Fortaleza com manifestações alérgicas exacerbadas na época de floração do cajueiro, o objetivo deste estudo foi produzir um extrato protéico a partir do pólen do cajueiro e identificar os alérgenos ainda não estudados presentes neste pólen. Doze pacientes residentes em Fortaleza, Nordeste do país, foram selecionados com base na história de rinite alérgica persistente e agravamento dos sintomas no momento da floração do cajueiro. Foi selecionado outro grupo com rinite alérgica que vive na mesma região, entretanto não apresenta relação clínica com a época de floração. Além disso, foram incluídos 5 indivíduos não-atópicos e expostos ao cajueiro como grupo controle. O soro desses pacientes foi testado em Western Blot 1D e 2D (WB) e as proteínas selecionadas foram submetidas à espectrometria de massas para identificação. Os epitopos foram preditos in silico pesquisando sequências detectadas por massa contra bases de dados de epítopos já conhecidos. Foi possível identificar alguns homólogos de alérgenos de outros pólens, como isoflavona redutase (Bet v 6), beta-1,3-glucanase (Ole e 9), proteína de choque térmico 70kDa (Cor a 10), além de outras proteínas que podem representar novos alergénios, tais como aminociclase, glutamina sintetase, fosfoglucomutase, ?-1,4-glucano-proteína-sintase, factor de alongamento 2 e biotina carboxilase, entre outros. A predição de epítopos revelou a possibilidade de reatividade cruzada com outros alérgenos de pólen conhecidos, tais como Phl p 4, Mal d 1, além de outros aeroalérgenos que também apareceram. Esta é a primeira descrição da alergia ao pólen do caju mostrando a reatividade específica de IgE no soros dos pacientes. A caracterização imunológica e estrutural de novos alérgenos, além de auxiliar no diagnóstico e tratamento de alergias não descritas, oferece ferramentas para prever epítopos e produzir moléculas hipoalergênicas nesta era da medicina de precisão / Pollinosis is a seasonal allergic rhinitis that develops due to pollens sensitization. Symptoms are manifested always in the same period of the year. Clinically, it is characterized by rhinoconjunctivitis and/or asthma. Allergen-specific immunotherapy is the only available treatment that can modify the natural course of the disease, however, it relies on the correct identification of the triggering allergen. Considering this and the number of patients attending the Allergy Clinic at University of Fortaleza with exacerbation of allergic symptoms during cashew flowering period, the aim of this study was to produce a protein extract from cashew tree pollen and identify the allergens not yet studied. Twelve patients living in Fortaleza, Northeast of country, were selected based on history of persistent allergic rhinitis and aggravation of symptoms at the time of cashew tree flowering. Another group living in the same region with allergic rhinitis without clinical relation with the flowering season was selected. Also 5 non-atopic subjects exposed to cashew tree were selected as a control group. The serum of these patients was tested for 1D and 2D Western Blotting (WB) and selected proteins were submitted to mass spectrometry for identification. Epitopes were predicted by in silico search comparing detected sequences against epitope databases. It was possible to identify some homologs of allergens from other pollens such as isoflavone reductase (Bet v 6), beta-1,3-glucanase (Ole e 9), heat shock protein 70kDa (Cor a 10), besides other proteins that might represent novel allergens, such aminociclase, glutamina sintetase, phosphoglucomutase, alpha-1,4-glucan-protein-synthase, elongation factor 2 and biotin carboxylase among others. The epitope prediction revealed the possibility of cross-reactivity with other known pollen allergens such as Phl p 4, Mal d 1 and other aeroallergens also appeared. This is the first description of cashew pollen allergy showing specific IgE reactivity of patients\' sera. The immunological and structural characterization of new allergens, besides aiding the diagnosis and treatment of non-described allergies, offers tools for predicting epitopes and producing hypoallergenic molecules in this era of precision medicine
104

Efeito da variação sazonal na produção de compostos ativos em Tithonia diversifolia (HEMSL) Gray, utilizando ensaio com microrganismos. / Effects of seasonal variation upon production of active compounds in tithonia diversifolia (HEMSL) Gray using microrganisms bioassay.

Silva, Paula Carolina de Simoni Cordeiro e 13 August 2004 (has links)
A variação sazonal na produção de compostos secundários em Tithonia diversifolia (Hemsl) Gray foi investigada desde a primavera de 2002 até o inverno de 2003. Coletas bimensais foram realizadas com posterior extração e fracionamento do material vegetal (folhas e flores). As amostras foram monitoradas por CCD e analisadas quanto a atividade antimicrobiana contra Staphylococcus aureus, Escherichia coli, Salmonella choterasuis e Pseudomonas aeruginosa, pelo método de microplaca. Os perfis cromatográficos foral distintos para as diferentes épocas do ano, sendo evidenciada a presença de um grupo de substâncias em maior quantidade no mês de Abril de 2003 (outono), período de pré-florada desta espécie. Os extratos foram ativos para apenas dois microrganismos dentre os quatro testados. Algumas frações apresentaram CIM (concentração inibitória mínima) significativa (<1mg/mL). / The seasonal variation upon production of active compounds in Tithonia diversifolia (Hemsl) Gray was investigated from spring of 2002 until winter of 2003. Leaf samples were collected every three months for posterior extraction and analysis . The samples were monitored by Thin Layer Chromatography (TLC) and analyzed for anti-microbial activities on Staphylococcus aureus, Escherichia coli, Salmonella choterasuis and Pseudomonas aeruginosa, using micro-plate method. The TLC results showed a clear accumulation of active compounds during April . The extracts were active for only two microorganisms of a total of four studied.
105

Contribuição ao estudo da variação sazonal do fitoplâncton da represa Billings-São Paulo / Contribution to the study of the seasonal variation of the phytoplankton of Billings\' dam, Sao Paulo

Xavier, Miriam Borges 25 June 1979 (has links)
Coletas de amostras de água para o estudo do fitoplâncton foram feitas, quinzenalmente, de outubro de 1977 a setembro de 1978, na Represa Billings, em São Bernardo do Campo, Estado de São Paulo. Foram amostrados dois locais: estação 1, no braço do Rio Grande e estação 2, no braço do Rio Pequeno. Procurou-se efetuar um estudo sazonal característico de clima tropical e subtropical ao abranger períodos consecutivos de chuva e estiagem. A distribuição do \"standing-stock\" do fitoplâncton foi feita por contagem de organismos em UPA/ml e por determinação da clorofila a. Procurou-se relacionar os resultados obtidos referentes ao fitoplâncton com as variáveis fÍsicas e químicas estudadas, quais sejam: temperatura, cor, turbidez, transparência, condutividade elétrica, pH, oxigênio dissolvido, oxigênio consumido, amônia, nitrito, fosfato e sílica. O máximo quantitativo da população fitoplanctônica foi encontrado no período de estiagem. Qualitativamente, foi obtido no período de chuva. Geralmente, predominaram Mougeotia sp. (Chlorophyceae) na estação 1 e Microcystis aeruginosa (Cyanophyceae) na estação 2, ambas apresentaram variação sazonal acentuada, o que nao aconteceu com as Euglenophyceae, as Chrysophyceae e as Dinophyceae. A temperatura influencia a distribuição quantitativa do fitoplâncton; quando foram registradas temperaturas altas a abundância de fitoplâncton foi menor. Nas estações estudadas, os teores de amônia e nitrato apresentaram variação sazonal acentuada, sendo máximos no período de estiagem. Portanto, houve coincidência no desenvolvimento quantitativo do fitoplâncton e nutrientes (amônia e nitrato). Houve uma correspondência evidente entre os picos de oxigênio dissolvido e a porcentagem de saturação desse gás na água com o pico de fitoplâncton total, evidenciando a contribuição de oxigênio pela fotossíntese. Os dados obtidos referentes ao \"standingstock\" de fitoplâncton (clorofia a e contagem de organismos), nutrientes (amônia e nitrato) e oxigênio consumido indicam que a Represa Billings constitui um ambiente eutrófico. / Phytoplankton samples were collected every two weeks at two stations for a period of one year (Oct., 1977 - Sept., 1978). The station 1 is located at Rio Grande and station 2 at Rio Pequeno in the Billings Reservoir, São Bernardo do Campo, State of São Paulo. The standing stock of the phytoplankton was determined by organisms counting and chlorophyll-a determination. An attempt was made to correlate phytoplankton with environmental factors, such as: tide, temperature, color, turbidity, water transparence, electric condutivity, pH, dissolved oxygen, consumed oxygen, ammonia, nitrits, nitrates, phosphates and silica. The phytoplankton consisted mainly of Mougeotia sp. (Chlorophyceae) at station 1 and Microcytis aeruginosa (Cyanophyceae) at station 2. Both groups showed a marked seasonal variation, but Euglenophyceae, Chrysophyceae, and Dinophyceae did not show this pattern. The maximum of phytoplankton was recorded during the draught season. Qualitatively, however, the phytoplankton maximum was recorded during the rainy season. It was also noted an influence of the temperature over the quantitative distribution of the phytoplankton; at high temperatures the phytoplankton abundance was less significant. The ammonia and nitrates concentrations also showed a marked seasonal variation, their peaks attained during the drought period. Therefore, there was a coincidence in the quantitative development of phytoplankton and the amount of nutrients (ammonia and nitrates). The peaks of the dissolved oxygen content of the water, and of the oxygen saturation values were very much related to the phytoplankton peak, showing the oxygen contribution by photosinthesis. The data obtained which refer to the standing stock of phytoplankton (chlorophyll-a and organism counting), nutrients (ammonia and nitrate) and the consumed oxygen indicate that the Billings Reservoir constitutes an eutrophic environment.
106

Efeito da sazonalidade na dinâmica populacional de helmíntos gastrintestinais e susceptibilidade em equinos à pasto / Seasonality effect on population dynamics of gastrointestinal helminths and susceptibility in grazing horses

Saes, Isabela de Lima [UNESP] 19 December 2016 (has links)
Submitted by Isabela de Lima Saes null (isa.l.s@hotmail.com) on 2017-02-23T11:58:16Z No. of bitstreams: 1 Dissertação.pdf: 811344 bytes, checksum: bd9b7bb77b89fffdd99dbb1d3bbb7150 (MD5) / Rejected by LUIZA DE MENEZES ROMANETTO (luizamenezes@reitoria.unesp.br), reason: Solicitamos que realize uma nova submissão seguindo as orientações abaixo: O arquivo submetido está sem a ficha catalográfica. O arquivo submetido não contém o certificado de aprovação. Verifique na folha de rosto o texto "Qualificação de mestrado apresentada à Universidade Estadual Paulista “Julio Mesquita Filho” – UNESP, Câmpus experimental de Dracena, como parte das exigências para obtenção do título de Mestre em Ciência e Tecnologia Animal", o trecho gera dúvida se a versão submetida compreende versão de qualificação e não a dissertação final. A versão submetida por você é considerada a versão final da dissertação/tese, portanto não poderá ocorrer qualquer alteração em seu conteúdo após a aprovação. Corrija estas informações e realize uma nova submissão. Agradecemos a compreensão. on 2017-02-24T17:33:09Z (GMT) / Submitted by Isabela de Lima Saes null (isa.l.s@hotmail.com) on 2017-10-11T20:18:34Z No. of bitstreams: 1 Dissertação (Reparado) (1).pdf: 1423930 bytes, checksum: 9bb924a4ef7932d59cd7a80e6bfe39aa (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-10-11T20:34:04Z (GMT) No. of bitstreams: 1 saes_il_me_ilha.pdf: 1423930 bytes, checksum: 9bb924a4ef7932d59cd7a80e6bfe39aa (MD5) / Made available in DSpace on 2017-10-11T20:34:04Z (GMT). No. of bitstreams: 1 saes_il_me_ilha.pdf: 1423930 bytes, checksum: 9bb924a4ef7932d59cd7a80e6bfe39aa (MD5) Previous issue date: 2016-12-19 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Infecções parasitárias são extremamente importantes em equinos, devido aos prejuízos causados, e tendem a acometê-los durante toda a vida do animal. No entanto, a prevalência de helmintos pode aumentar ou diminuir, nas dependências de fatores climáticos ou susceptibilidade do hospedeiro. Diante disso, avaliou-se a dinâmica sazonal da infecção helmíntica em equinos mantidos a pasto, a influência das diferentes características climáticas das estações do ano sobre o grau de verminose, a susceptibilidade individual e por categoria e identificar as épocas e as categorias de equinos com maior incidência de helmintoses. Foi utilizado um rebanho com 104 equinos, mestiços, classificados em diferentes categorias. Foram realizadas coletas individuais de fezes a cada 28 dias para a contagem de ovos por grama de fezes (OPG) e coproculturas para identificação de larvas. Também foram realizadas coletas de sangue para analisar possíveis alterações no hemograma dos animais associados à infecção helmíntica. Todos os animais foram pesados individualmente a cada coleta, e avaliado o escore de condição corporal, juntamente com uma avaliação clínica dos animais. Diariamente foram aferidas as temperaturas média, umidade do ar e precipitação na propriedade. Foram calculadas e apresentadas estatísticas descritivas das variáveis observadas e sua variação sequencial no tempo visando avaliar a dinâmica populacional de helmintos em equinos a pasto. As categorias que mais foram acometidas pelos helmintos foram os potros e os idosos, apresentando médias 1271,9 e 1186,5 de OPG, respectivamente. As médias de OPG encontradas nas estações da primavera, verão, outono e inverno foram, respectivamente, 1042,1; 1508,9; 817,8 e 571,1, onde todas as médias diferem significativamente entre si. Na avaliação da condição corporal foi possível observar que os animais idosos foram os que apresentaram menor ECC em todas as estações: primavera, verão, outono e inverno, sendo observado escore 3,83; 3,68; 3,56 e 3,14, respectivamente. Os resultados das coproculturas mostraram que 100% dos helmintos gastrintestinais encontrados eram da família dos pequenos estrôngilos, os Ciatostomíneos. Não foram encontradas muitas alterações nos exames hematológicos dos animais e, a maioria deles não manifestou qualquer tipo de sinais clínicos associado à doença parasitária. Foi possível concluir que a estação que os animais mais são acometidos pela verminose é no verão e que as categorias mais susceptíveis à infecção helmíntica são os potros e os animais idosos. / Parasitic infections are extremely important in horses due to the damages caused, and tend to afflict them throughout the life of the animal. However, the prevalence of helminths may increase or decrease, in the premises of climatic factors and host susceptibility. Therefore, we evaluated the seasonal dynamics of helminth infection in horses kept at pasture. a herd was used with 104 crossbred horses, classified into different categories according to age and sex. Individual fecal samples were taken every 28 days for the eggs per gram of feces (OPG) and stool cultures for identification of larvae. Also blood samples were taken to analyze possible changes in the blood count of the animals associated with helminth infection. All animals were weighed individually every collection, and rated the body condition score, along with a clinical evaluation of the animals. Daily average temperatures were measured the, humidity and rainfall on the property. Descriptive statistics of the observed variables were calculated and presented and their sequential variation in time to evaluate the population dynamics of helminths in horses grazing. The categories that were most affected by helminths were foals and elderly, with averages of OPG 1271.9 and 1186.5, respectively. The average OPG found in spring seasons, summer, autumn and winter were respectively 1042.1; 1508.9; 817.8 and 571.1, which all means differ significantly. In the evaluation of body condition was observed that the aged animals showed the lowest ECC in all seasons: spring, summer, autumn and winter, being observed score 3.83; 3.68; 3.56 and 3.14, respectively. The results of stool cultures showed that 100% of gastrointestinal helminths were found family of small strongyles the Ciatostomíneos. There were no changes in blood tests of animals and most of them did not show any clinical signs associated with the parasitic disease. It was concluded that the station that animals are more affected by worms is in the summer and that the most likely categories to helminth infection are younger foals and older animals.
107

Contribuição ao estudo da variação sazonal do fitoplâncton da represa Billings-São Paulo / Contribution to the study of the seasonal variation of the phytoplankton of Billings\' dam, Sao Paulo

Miriam Borges Xavier 25 June 1979 (has links)
Coletas de amostras de água para o estudo do fitoplâncton foram feitas, quinzenalmente, de outubro de 1977 a setembro de 1978, na Represa Billings, em São Bernardo do Campo, Estado de São Paulo. Foram amostrados dois locais: estação 1, no braço do Rio Grande e estação 2, no braço do Rio Pequeno. Procurou-se efetuar um estudo sazonal característico de clima tropical e subtropical ao abranger períodos consecutivos de chuva e estiagem. A distribuição do \"standing-stock\" do fitoplâncton foi feita por contagem de organismos em UPA/ml e por determinação da clorofila a. Procurou-se relacionar os resultados obtidos referentes ao fitoplâncton com as variáveis fÍsicas e químicas estudadas, quais sejam: temperatura, cor, turbidez, transparência, condutividade elétrica, pH, oxigênio dissolvido, oxigênio consumido, amônia, nitrito, fosfato e sílica. O máximo quantitativo da população fitoplanctônica foi encontrado no período de estiagem. Qualitativamente, foi obtido no período de chuva. Geralmente, predominaram Mougeotia sp. (Chlorophyceae) na estação 1 e Microcystis aeruginosa (Cyanophyceae) na estação 2, ambas apresentaram variação sazonal acentuada, o que nao aconteceu com as Euglenophyceae, as Chrysophyceae e as Dinophyceae. A temperatura influencia a distribuição quantitativa do fitoplâncton; quando foram registradas temperaturas altas a abundância de fitoplâncton foi menor. Nas estações estudadas, os teores de amônia e nitrato apresentaram variação sazonal acentuada, sendo máximos no período de estiagem. Portanto, houve coincidência no desenvolvimento quantitativo do fitoplâncton e nutrientes (amônia e nitrato). Houve uma correspondência evidente entre os picos de oxigênio dissolvido e a porcentagem de saturação desse gás na água com o pico de fitoplâncton total, evidenciando a contribuição de oxigênio pela fotossíntese. Os dados obtidos referentes ao \"standingstock\" de fitoplâncton (clorofia a e contagem de organismos), nutrientes (amônia e nitrato) e oxigênio consumido indicam que a Represa Billings constitui um ambiente eutrófico. / Phytoplankton samples were collected every two weeks at two stations for a period of one year (Oct., 1977 - Sept., 1978). The station 1 is located at Rio Grande and station 2 at Rio Pequeno in the Billings Reservoir, São Bernardo do Campo, State of São Paulo. The standing stock of the phytoplankton was determined by organisms counting and chlorophyll-a determination. An attempt was made to correlate phytoplankton with environmental factors, such as: tide, temperature, color, turbidity, water transparence, electric condutivity, pH, dissolved oxygen, consumed oxygen, ammonia, nitrits, nitrates, phosphates and silica. The phytoplankton consisted mainly of Mougeotia sp. (Chlorophyceae) at station 1 and Microcytis aeruginosa (Cyanophyceae) at station 2. Both groups showed a marked seasonal variation, but Euglenophyceae, Chrysophyceae, and Dinophyceae did not show this pattern. The maximum of phytoplankton was recorded during the draught season. Qualitatively, however, the phytoplankton maximum was recorded during the rainy season. It was also noted an influence of the temperature over the quantitative distribution of the phytoplankton; at high temperatures the phytoplankton abundance was less significant. The ammonia and nitrates concentrations also showed a marked seasonal variation, their peaks attained during the drought period. Therefore, there was a coincidence in the quantitative development of phytoplankton and the amount of nutrients (ammonia and nitrates). The peaks of the dissolved oxygen content of the water, and of the oxygen saturation values were very much related to the phytoplankton peak, showing the oxygen contribution by photosinthesis. The data obtained which refer to the standing stock of phytoplankton (chlorophyll-a and organism counting), nutrients (ammonia and nitrate) and the consumed oxygen indicate that the Billings Reservoir constitutes an eutrophic environment.
108

Investigation into natural variation and adaptation of Arabidopsis thaliana in Edinburgh and the Lothians

Lim, Poay Ngin January 2013 (has links)
The use of Arabidopsis thaliana populations to understand the genetic basis for natural variation has been highlighted in recent years. The role of adaptation in natural variation remains of key interest. Here, natural variation in growth rate, flowering time and seed production were examined in local populations of A. thaliana from the Edinburgh area using a common garden approach. Growth rate and seed production were found to be highly genetically determined and sometimes correlated, and some genotypes were found to perform consistently better as winter annuals and others as summer annuals, suggesting that adaptation to different seasons might maintain natural variation locally. In order to dissect the environmental factors that could affect growth, these genotypes were also grown under controlled conditions. Photoperiod and temperature were identified as two of the seasonal variables to which different genotypes may be adapted. The relationship between growth rate and competition was also examined. In general, competition exaggerated the differences in performance between genotypes, although the identity of neighbours was observed to have an effect on both growth rate and fitness of A. thaliana in competition. To understand the genetic basis of growth rate variation, the genetic relationships between local populations was examined. Local accessions were usually found to be more closely related to each other than to world-wide accessions, suggesting that their variation did not reflect recent immigration. To examine the genetic architecture of growth rate variation, hybrids between local genotypes with different growth rates were used in QTL analysis. Four chromosomal regions were detected; these regions represent potential growth-rate associated QTL.
109

Stratospheric Polar Vortex Variability in the Northern Hemisphere: the Effects of Climate Change on Polar Vortex Trends and Future Projections

Rogers, John Earl 20 March 2019 (has links)
Regions that have experienced recent successive cold winters such as the Northeast of North America and Siberia have endured critical social and economic impacts from anomalous low temperatures in recent years, despite warming global temperatures. It is well known that the Tropospheric Polar Vortex (TPV), or jet stream, is a primary influence on many mid-latitude winter weather patterns. However, the strong circumpolar westerlies that maximize at around 60° latitude just above the tropopause, known as the Stratospheric Polar Vortex (SPV), can affect tropospheric circulation and thus winter weather in the Northern Hemisphere. Strong upward propagating waves can affect the geographic extent and strength of the SPV resulting in a weakened polar vortex state, which can in turn bring persistent weather events to the mid-latitudes. Here, an index of SPV spatiotemporal variability is presented using observation based analysis of zonal wind and geopotential height to show changes in SPV behavior at a seasonal scale from 1950-2018. Utilizing the CMIP5 suite of global climate models, historical and projected simulations of the SPV's climatological extent and strength are analyzed from 1915 to the end of this century, taking into account models with enhanced stratospheric representation. Simulated results are largely consistent with trends in the observational data, which suggest continued increases in average SPV size throughout this century. If future SPV disturbances increase in frequency, there could be negative impacts in ecosystem and agricultural health, infrastructure damage, and to human safety. A more advanced understanding of SPV trends and anomalous events could improve forecasts of cold air outbreaks (CAOs) and severe or persistent winter weather.
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Distribuição ecológica das comunidades de macroalgas de ambientes lóticos em duas unidades de conservação abrangendo os biomas da Floresta Estacional Semidecidual e Campos no estado do Paraná /

Oliveira, Régis de Campos. January 2011 (has links)
Orientador: Ciro Cezar Zanini Branco / Banca: Rogério Antonio Krupek / Banca: Cleto Kaveski Peres / Resumo: Estudos anteriores sugerem que, aparentemente, existem padrões específicos para descrever a composição e a estrutura das comunidades de macroalgas em ambientes lóticos em função das características do bioma ao qual estão inseridos. Neste contexto, a presente dissertação objetivou avaliar, de forma comparativa, a composição, a estrutura das comunidades e a distribuição espacial das comunidades de macroalgas lóticas de duas unidades de conservação (UCs) com biomas distintos: Campos no Parque Estadual de Vila Velha (PVV) e Floresta Estacional Semidecidual no Parque Nacional do Iguaçu (PNI). Em adição, pretendeu-se comparar as comunidades de macroalgas nas quatro estações do ano, a fim de se verificar a possível existência de padrões temporais. As amostragens foram realizadas em 5 segmentos de riacho de 10 m de extensão, em cada UC, através da técnica da transeção, onde as variáveis abióticas (temperatura, oxigênio, pH, condutividade, turbidez, profundidade e velocidade da correnteza) foram mensuradas, assim como a presença e a abundância de cada espécie de macroalga. Estes parâmetros bióticos foram avaliados através da análise visual do leito do rio/riacho. As amostragens foram feitas uma vez a cada estação do ano. O estudo taxonômico registrou 37 macroalgas no total, sendo 16 táxons de ocorrência exclusiva no PVV, 18 táxons de ocorrência exclusiva no PNI e apenas 3 táxons com ocorrência em ambos os parques (Phormidium retzii, Hildenbrandia angolensis e Batrachospermum puiggarianum). O táxon com maior ocorrência no PVV foi o Zygogonium sp. (9 ocorrências), e no PNI o estágio "Chantransia" pygmaea foi o que ocorreu em maior número de pontos amostrados (15). Em relação aos tipos morfológicos, foram encontrados: filamentos livres (24%), filamentos gelatinosos (22%)... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Previous studies suggest that, apparently, there are specific standards to describe the structure and composition of macroalgae communities in lotic environments depending on the characteristics of the biome to which they belong. In this context, the present study aimed to evaluate, comparatively, the floristic composition, community structure and spatial distribution of lotic macroalgae communities from protected areas (PAs) with two distinct biomes, Grassland on Vila Velha State Park (VVP) and Semideciduous Seasonal Forest on the Iguazu National Park (INP). In addition, we intended to compare the macroalgal communities in the four seasons, to verify the possible existence of temporal patterns. The sampling sites were carried out from five segments of stream, 10 m length, in each PA, by means of the transect technique, where the environmental variables (temperature, oxygen, pH, conductivity, turbidity, depth and current velocity) were measured, as well the presence and abundance of each species of seaweed. These biotic parameters were evaluated using visual analysis of stream/river. The samplings were taken once every season. The taxonomic study recorded 37 macroalgae in total, with 16 taxa occurring exclusively in VVP, 18 taxa occurring exclusively in INP and only three taxa occurring in both parks (Phormidium retzii, Hildenbrand angolensis and Batrachospermum puiggarianum). The taxon with the highest frequency of occurrence in the VVP was Zygogonium sp. (9 sites), whereas in INP "Chantransia" pygmaea is what happened to a greater number of sampled sites (15). Respecting the morphological types were found: free filaments (24%), gelatinous filaments (22%), mats (19%), gelatinous colonies... (Complete abstract click electronic access below) / Mestre

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