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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.
1

Performance Evaluation of Flexible Pavements in Alberta Using Falling Weight Deflectometer Data

Norouzi, Meisam Unknown Date
No description available.
2

Seasonal variation in the number of dogs and cats entering four animal shelters in Mississippi and the characterisitics [i.e. characteristics] influencing their adoption

Lefebvre, Sarah Elizabeth 07 August 2010 (has links)
The pet overpopulation problem is a multiactorial problem that many organizations such as animal shelters attempt to manage. Many studies have focused on the reasons animals are relinquished by their owners but few have also looked at the characteristics that may influence adoption. Identifying which characteristics that influence adoption may help shelters provide more detailed adoption programs based on their dog and cat profile. Increases in the number of dogs and cats entering animal shelters during the spring and summer month is a perception among shelter staff. Investigating the seasonal trends in the number of animals entering a shelter may help the facility prepare to provide additional space and resources. The focus of this study was to identify any seasonal variation in the number of dogs and cats entering animal shelters in Mississippi and to determine the characteristics of dogs and cats that influenced their adoption.
3

LONG-TERM VARIATIONS IN THE HIGH-LATITUDE PLASMA FLOWS INFERRED FROM SUPERDARN RADAR DATA

2015 April 1900 (has links)
ABSTRACT This Thesis investigates ionospheric plasma flows (commonly referred to as “convection”) at high latitudes with the objectives to assess seasonal and solar cycle variations in the shape of the flow patterns and the flow intensity in terms of external drivers of the flow, first of all the magnitude and orientation of the interplanetary magnetic field (IMF). Multi-year (2001-1011) line-of-sight Doppler velocity data collected by the Super Dual Auroral Network (SuperDARN) HF radars are considered. Two approaches are used: 1) analysis of monthly-averaged 2-dimentional patterns inferred from data of all SuperDARN radars operated and 2) analysis of near magnetic noon data from only two SuperDARN radars, Rankin Inlet and Inuvik monitoring meridional component of the flow in the near North Pole areas (polar cap). We show and discuss seasonal and solar cycle variations of three characteristics of the flows: magnetic latitudes of the region where plasma flow direction changes from toward the noon to away from the noon (convection reversal boundary), the magnetic local time location of the near noon region with stagnated flow (throat region) and, finally, the magnitude of the flow. All three parameters show trends, although not strong and consistent all the time, which agrees with previous publications where different analysis approaches and more limited data sets were used. For two specific points, one at the magnetic latitude of 72 degrees, representing the auroral oval latitudes (region where optical arcs occur most frequently) and the other one at 82 degrees, representing the polar cap latitudes we demonstrate that the average flow magnitude increases with the IMF intensity, and the effect is much stronger for the negative vertical component of the IMF Bz. In our second approach we demonstrate that the flow velocity increases almost linearly with an increase of the reconnection electric fields characterizing processes of interaction between the solar wind/IMF and the Earth`s magnetic dipole. Saturation effect is seen for strongest electric field. More clear seasonal effects are noticeable in these data; the velocity response to the reconnection electric field enhancement is stronger summer (winter) time for positive (negative) IMF Bz. The data are consistent with previous reports, where highly smoothed velocity data were considered.
4

Spatiotemporal distribution of larval fish assemblage in the coastal waters off Kaohsiung and Pingtung, Taiwan

Wu, Chia-Ching 12 September 2012 (has links)
To clarify the spatiotemporal distribution of the winter and spring larval fish assemblage in the coastal waters off Kaohsiung and Pingtung, Taiwan, larval fishes were collected during four research cruises by conducting 35 tows of the larval net in coastal waters off Zuoying, Linyuan, Linban and Fangliao in January and March 2009 and in coastal waters off Linyuan adjacent to the Kaoping River estuary in January and March 2010. Water temperature, salinity and dissolved oxygen were measured during the sampling of the fish larvae. Seawater samples were also collected for analyzing concentrations of nutrient salts. In 2009, a total of 2,023 fish larvae, representing 38 families and 74 species, were collected. The fish larvae assemblage exhibited seasonal variation in both abundance and species composition. The abundance (460 ind./1000m3) and the number of species (34 families and 66 species) of the fish larvae collected in March were higher than those (28 ind./1000m3, 14 families and 27 species) collected in January. Fish larvae also exhibited spatial variation in species composition. In January, the most dominant families of fish larvae were: Myctophidae off Linyuan, Sparidae off Linban and Nomeidae off Fangliao. In March, in the northward coastal waters off Linyuan Scombridae was the most dominant family, and in the southward coastal waters off Linyuan, Clupeidae and Sillaginidae were the dominant families. No significant differences existed in the abundance of fish larvae among the sampling areas, but the abundance of fish larvae in the sampling sites off Linyuan and Linban tended to be strongly influenced by tide. In 2010, a total of 1,959 fish larvae, representing 39 families and 59 species, were collected. These fish larvae showed diurnal and seasonal variations in abundance and in species composition. The abundance (767 ind./1000m3) and the number of species (39 families and 55 species) of the fish larvae in March were higher compared with those (26 ind./1000m3, 16 families and 25 species) in January. Moreover, the abundance of fish larvae in the nighttime was higher than that in the daytime. In March, the most dominant family in the daytime was Serranidae, whereas the most dominant family in the nighttime was Myctophidae, indicating the diurnal migration of Myctophidae these larvae. Cluster analysis indicated that the abundance and species composition of the fish larvae differed between January and March in 2009. The difference in species composition among the four sampling areas was only found significant for the fish larvae collected in the coastal waters off Fangliao in winter, and the most influenced families were Nomeidae and Myctophidae. In 2010, seasonal variations were found in the abundance and species composition of the fish larvae, and the abundance of the fish larvae showed the difference between nearshore and inshore sampling sites in the nighttime in winter. In spring, the fish larvae were all inshore fishes, but the species composition had annual variation. The temperature and salinity data obtained in the sampling sites conformed to the surface seawater of South China Sea, indicating that the occurrence of the dominant family Scombridae may be related to the seawater of South China Sea.
5

Vitamin D status in winter and summer among nurses and implications for cancer etiology

WALLINGFORD, SARAH 23 September 2009 (has links)
Background: Recent research indicates that inadequate vitamin D status may incur increased cancer risk, particularly for breast and colon cancer. Cutaneous generation of vitamin D through direct absorption of summer sunlight is considered the principal source of vitamin D; however, at latitudes above 40ºN, UVB rays are insufficient to permit cutaneous synthesis during winter. Vitamin D can also be obtained from natural and fortified dietary sources and through supplement use, although dietary reference intake values do not seem to compensate for restricted cutaneous synthesis in winter. Objectives: To determine the prevalence of vitamin D insufficiency post-winter and post-summer, to determine the seasonal variation in 25-hydroxyvitamin D (25(OH)D) levels, and to investigate determinants of 25(OH)D concentrations. Methods: A cross-sectional study of vitamin D status post-winter and post-summer was conducted among 49 premenopausal rotating shift nurses at Kingston General Hospital. In each season, vitamin D levels were measured using a radioimmunoassay to quantify serum 25(OH)D from fasting blood samples, and personal, lifestyle, and dietary factors potentially influencing vitamin D levels were assessed from a self-report questionnaire. Nurses were classified as vitamin D sufficient (>30ng/mL) or insufficient (≤30ng/mL). Results: A statistically significant difference was found between mean serum 25(OH)D concentrations post-winter (32.6ng/mL) and post-summer (42.5ng/mL) (p=0.0003). The prevalence of vitamin D insufficiency post-winter was 49% compared to 24% post-summer p=0.02). Tanning bed use was associated with significantly higher winter serum 25(OH)D levels was tanning bed, while controlling for age, BMI, and vitamin D-fortified yogurt consumption (R2=0.41, p=0.007). For summer, predictors of higher serum 25(OH)D levels were supplement use and tanning bed use in the past six months, while controlling for age, BMI, and beef/veal consumption (R2=0.53, p=0.001). Conclusions: Vitamin D insufficiency was prevalent both post-winter and post-summer, but with much higher prevalence post-winter. Controlling for age and BMI, tanning bed use was a determinant of serum 25(OH)D concentrations in both seasons, while fortified yogurt consumption also contributed in winter, and beef/veal consumption and supplement use contributed in summer. These findings support the need to improve vitamin D status among this population, and to increase the dietary reference intake values and supplement recommendations. / Thesis (Master, Community Health & Epidemiology) -- Queen's University, 2009-09-22 15:35:27.652
6

Seasonal carbohydrate allocation in Big Tooth Aspen (Populus Grandidentata Michx.) and Northern Red Oak (Quercus Rubra L.) from northern lower Michigan

Flower, Charles Elliot 20 September 2007 (has links)
No description available.
7

An analysis of the meroplankton assemblages of Station L4 and the development and application of molecular techniques to aid taxonomic resolution

Highfield, James January 2012 (has links)
Zooplankton data from the 1988-2007 Station L4 time-series were used to determine inter-and intra-annual patterns of meroplankton community change at Station L4, Plymouth, UK. Abundances were calculated for five groups: Cirripedia, Decapoda, Polychaeta, Echinodermata and Bivalvia. Analyses showed that, while there is some annual variability, seasonal variation accounts for the major changes in the meroplanktonic community composition throughout the time-series. Cirripedia were the only group to show any significant change in abundance over the time-series. Further sampling at the study site produced data at a finer taxonomic resolution allowing for the analyses of the seasonal cycles of abundance of previously unresolved families and genera from the 1988-2007 time-series. A similar pattern was shown to that seen in the earlier time-series with no evidence of major changes in the meroplanktonic community being found. Comparison with historical data taken from Lebour (1947) showed little evidence of major variation in meroplanktonic species composition. The limitations of traditional methods of taxonomic resolution were highlighted during these analyses and led to the investigation of molecular techniques as a viable aid to identification. Bivalve larval samples were identified to species in many cases using PCR and sequencing reactions focussing on the 18S rRNA gene. Larvae of Phaxas pellucidus were shown to be the most common, and further analysis revealed the presence of two groups of species within the data over the time sampled, comprising the larvae of several hard-substrata species. Development of an RFLP technique focussing on the mtCOI gene, allowed for the successful discrimination of porcellanid larvae to species that were unable to be resolved morphologically. Long-term data-sets play an important role in revealing the long-term patterns of community composition and abundance of meroplanktonic larvae and should be continued to identify those patterns not evident over the time-period studied. Molecular techniques were valuable in aiding the taxonomic resolution of meroplanktonic larvae, allowing previously unknown patterns of species diversity and richness to be ascertained.
8

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.
9

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.
10

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.

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