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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.
91

LARGE-SCALE ROOT ZONE SOIL MOISTURE ESTIMATION USING DATA-DRIVEN METHODS

Pan, Xiaojun 11 1900 (has links)
Soil moisture is an important variable in many environmental researches and application areas as it affects the interactions between atmosphere and land surface by controlling the energy and water exchange. The current measurement techniques are insufficient to acquire accurate large-scale root zone soil moisture (RZSM) data at the spatial resolution of interest. Though assorted models have been successfully applied in relatively small areas to estimate RZSM, the large-scale estimation is still facing challenges as it requires the flexibility and practicality of the models for the applications under various conditions. Though physically based soil moisture models are widely used, the errors in model physics affect the flexibility of these models meanwhile their large demand of data and computational resources reduces the practicality. On the contrary, the statistical and data-driven methods have high potential but their applications for large-scale RZSM estimation have not been fully explored. To develop feasible models for large-scale RZSM estimation using the surface observations, artificial neural networks, specifically multilayer perceptrons (MLPs), were applied in this study to estimate RZSM at the depths of 20cm and 50cm, using the data of 557 stations in the United States. Two experiments including four models were developed and the input variables of the models were carefully selected. The sensitivity analysis found that surface soil moisture and the cumulative rainfall, snowfall, air temperature and surface soil temperature were important inputs. If given soil texture data as inputs, the models achieved better performance and were extremely sensitive to them. The results showed that the MLPs were effective and flexible for the estimation of soil moisture at 20cm under various climate types and were insensitive to the potential errors in soil moisture datasets. However, the results of the estimation at 50cm are not as good as that of the 20cm. / Thesis / Master of Science (MSc)
92

Comparison of Normalization Methods in Microarray Analysis

Yang, Rong 04 1900 (has links)
<p> DNA microarrays can measure the gene expression of thousands of genes at a time to identify differentially expressed genes. The Affymetrix GeneChip system is a platform for the high-density oligonucleotide microarray to measure gene expression using hundreds of thousands of 25-mer oligonucleotide probes.</p> <p> To deal with Affymetrix microarray data, there are three stages of preprocessing to produce gene expression measurements/values. These are background correction, normalization and summarization. At each stage, numerous methods have been developed.</p> <p> Our study is based on Affymetrix MG_U74Av2 chip with 12488 probe sets. Two strains of mice called NOR and NOR.NOD_Idd4/11 mouse are hybridized for the experiment. We apply a number of commonly used and state-of-art normalization methods to the data set, thus compute the expression measurements for different methods. The major methods we discuss include Robust Multi-chip Average (RMA), MAS 5.0, GCRMA, PLIER and dChip.</p> <p> Comparisons in terms of correlation coefficient, pairwise expression measures plot, fold change and Significance Analysis of Microarray (SAM) are conducted.</p> / Thesis / Master of Science (MSc)
93

Pharmacokinetic and pharmacodynamic investigations of select natural products and nutraceuticals for human and veterinary health

Martinez, Stephanie January 2013 (has links)
Natural products are teeming with potential therapeutic agents. One group of compounds, polyphenols, from plants, exhibit anti-cancer, anti-inflammatory and anti-oxidant activities. Four polyphenolic compounds and their enantiomers were investigated in this thesis; the stilbene, 3-methoxypterostilbene, a structural analog of resveratrol, and the chiral prenylflavonoids from hops (Humulus lupulus L.); 8-prenylnaringenin, 6-prenylnaringenin and isoxanthohumol. A high performance liquid chromatography method for 3-methoxypterostilbene and enantiospecific liquid chromatography-mass spectrometry assays for the three prenylflavonoids were developed and validated. The methods allowed for quantification of these four polyphenols in biological samples and plant-based materials. Content analysis studies of 3-methoxypterostilbene and the three prenylflavonoids in traditional Chinese medicinal plants and hops-containing nutraceuticals were carried out, respectively. The pharmacokinetics of these four compounds were delineated through intravenous and oral administration in rats. 3-Methoxypterostilbene demonstrated greater bioavailability in rats than reported values for resveratrol. Enantiomeric differences in disposition parameters were observed for the three prenylflavonoids along with differences between compounds despite only small structural differences. The in vitro pharmacodynamics of these four compounds were elucidated including anti-oxidant, anti-inflammatory, anti-diabetic and cytochrome P450 modulation activities. All four compounds demonstrated a range of bioactivities related to chronic diseases and potential drug-botanical interactions. Further studies of polyphenols, especially clinical studies, are needed along with enantiospecific study when applicable to continue delineating the importance of bioactivity, pharmacokinetics and safety. Natural products are further developed into nutraceuticals and sold over-the-counter for both human and veterinary use but are not currently required to demonstrate efficacy prior to marketing. In the final section of this thesis, Phycox®, a multi-component veterinary nutraceutical for joint health was investigated for pharmacological activity in an in vitro model of canine osteoarthritis along with select constituents. A pilot single-dose pharmacokinetic study in dogs was also undertaken. Two liquid chromatography tandem mass spectrometry methods were developed and validated to detect constituents in serum. In vitro study results indicated that Phycox® was able to reduce inflammatory mediators similar to the NSAID, carprofen, and acute pharmacokinetic results revealed that detectable concentrations of glucosamine were evident in serum. It is suggested that further clinical studies of Phycox® are warranted to optimize its usage. / May 2016
94

Three-dimensional direct simulation Monte-Carlo modeling of the coma of comet 67P/Churyumov-Gerasimenko observed by the VIRTIS and ROSINA instruments on board Rosetta

Fougere, N., Altwegg, K., Berthelier, J.-J., Bieler, A., Bockelée-Morvan, D., Calmonte, U., Capaccioni, F., Combi, M. R., De Keyser, J., Debout, V., Erard, S., Fiethe, B., Filacchione, G., Fink, U., Fuselier, S. A., Gombosi, T. I., Hansen, K. C., Hässig, M., Huang, Z., Le Roy, L., Leyrat, C., Migliorini, A., Piccioni, G., Rinaldi, G., Rubin, M., Shou, Y., Tenishev, V., Toth, G., Tzou, C.-Y. 30 March 2016 (has links)
Context. Since its rendezvous with comet 67P/Churyumov-Gerasimenko (67P), the Rosetta spacecraft has provided invaluable information contributing to our understanding of the cometary environment. On board, the VIRTIS and ROSINA instruments can both measure gas parameters in the rarefied cometary atmosphere, the so-called coma, and provide complementary results with remote sensing and in situ measurement techniques, respectively. The data from both ROSINA and VIRTIS instruments suggest that the source regions of H2O and CO2 are not uniformly distributed over the surface of the nucleus even after accounting for the changing solar illumination of the irregularly shaped rotating nucleus. The source regions of H2O and CO2 are also relatively different from one another. Aims. The use of a combination of a formal numerical data inversion method with a fully kinetic coma model is a way to correlate and interpret the information provided by these two instruments to fully understand the volatile environment and activity of comet 67P. Methods. In this work, the nonuniformity of the outgassing activity at the surface of the nucleus is described by spherical harmonics and constrained by ROSINA-DFMS data. This activity distribution is coupled with the local illumination to describe the inner boundary conditions of a 3D direct simulation Monte-Carlo (DSMC) approach using the Adaptive Mesh Particle Simulator (AMPS) code applied to the H2O and CO2 coma of comet 67P. Results. We obtain activity distribution of H2O and CO2 showing a dominant source of H2O in the Hapi region, while more CO2 is produced in the southern hemisphere. The resulting model outputs are analyzed and compared with VIRTIS-M/-H and ROSINADFMS measurements, showing much better agreement between model and data than a simpler model assuming a uniform surface activity. The evolution of the H2O and CO2 production rates with heliocentric distance are derived accurately from the coma model showing agreement between the observations from the different instruments and ground-based observations. Conclusions. We derive the activity distributions for H2O and CO2 at the surface of the nucleus described in spherical harmonics, which we couple to the local solar illumination to constitute the boundary conditions of our coma model. The model presented reproduces the coma observations made by the ROSINA and VIRTIS instruments on board the Rosetta spacecraft showing our understanding of the physics of 67P’s coma. This model can be used for further data analyses, such as dust modeling, in a future work.
95

The modifiable areal unit phenomenon : an investigation into the scale effect using UK census data

Manley, David J. January 2006 (has links)
The Modifiable Areal Unit Phenomenon (MAUP) has traditionally been regarded as a problem in the analysis of spatial data organised in areal units. However, the approach adopted here is that the MAUP provides an opportunity to gain information about the data under investigation. Crucially, attempts to remove the MAUP from spatial data are regarded as an attempt to remove the geography. Therefore, the work seeks to provide an insight to the causes of, and information behind, the MAUP. The data used is from the 1991 Census of Great Britain. This was chosen over 2001 data due to the availability of individual level data. These data are of key importance to the methods employed. The methods seek to provide evidence of the magnitude of the MAUP, and more specifically the scale effect in the GB Census. This evidence is built on using correlation analysis to demonstrate the statistical significance of the MAUP. Having established the relevance of the MAUP in the context of current geographical research, the factors that contribute to the incidence of the MAUP are considered, and it is noted that a wide range of influences are important. These include the population size and density of an area, along with proportion of a variable. This discussion also recognises the importance of homogeneity as an influential factor, something that is referenced throughout the work. Finally, a search is made for spatial processes. This uses spatial autocorrelation and multilevel modelling to investigate the impact spatial processes have in a range of SAR Districts, like Glasgow, Reigate and Huntingdonshire, on the scale effect. The research is brought together, not to solve the MAUP but to provide an insight into the factors that cause the MAUP, and demonstrate the usefulness of the MAUP as a concept rather than a problem.
96

Small-scale structures in the upper atmosphere of the Sun

Barczynski, Krzysztof 11 April 2017 (has links)
No description available.
97

Formal methods for the analysis of wireless network protocols

Fruth, Matthias January 2011 (has links)
In this thesis, we present novel software technology for the analysis of wireless networks, an emerging area of computer science. To address the widely acknowledged lack of formal foundations in this field, probabilistic model checking, a formal method for verification and performance analysis, is used. Contrary to test and simulation, it systematically explores the full state space and therefore allows reasoning about all possible behaviours of a system. This thesis contributes to design, modelling, and analysis of ad-hoc networks and randomised distributed coordination protocols. First, we present a new hybrid approach that effectively combines probabilistic model checking and state-of-the-art models from the simulation community in order to improve the reliability of design and analysis of wireless sensor networks and their protocols. We describe algorithms for the automated generation of models for both analysis methods and their implementation in a tool. Second, we study spatial properties of wireless sensor networks, mainly with respect to Quality of Service and energy properties. Third, we investigate the contention resolution protocol of the networking standard ZigBee. We build a generic stochastic model for this protocol and analyse Quality of Service and energy properties of it. Furthermore, we assess the applicability of different interference models. Fourth, we explore slot allocation protocols, which serve as a bandwidth allocation mechanism for ad-hoc networks. We build a generic model for this class of protocols, study real-world protocols, and optimise protocol parameters with respect to Quality of Service and energy constraints. We combine this with the novel formalisms for wireless communication and interference models, and finally we optimise local (node) and global (network) routing policies. This is the first application of probabilistic model checking both to protocols of the ZigBee standard and protocols for slot allocation.
98

The International Deep Planet Survey

Galicher, R., Marois, C., Macintosh, B., Zuckerman, B., Barman, T., Konopacky, Q., Song, I., Patience, J., Lafrenière, D., Doyon, R., Nielsen, E. L. 13 October 2016 (has links)
Context. Radial velocity and transit methods are effective for the study of short orbital period exoplanets but they hardly probe objects at large separations for which direct imaging can be used. Aims. We carried out the international deep planet survey of 292 young nearby stars to search for giant exoplanets and determine their frequency. Methods. We developed a pipeline for a uniform processing of all the data that we have recorded with NIRC2/Keck II, NIRI/Gemini North, NICI/Gemini South, and NACO/VLT for 14 yr. The pipeline first applies cosmetic corrections and then reduces the speckle intensity to enhance the contrast in the images. Results. The main result of the international deep planet survey is the discovery of the HR8799 exoplanets. We also detected 59 visual multiple systems including 16 new binary stars and 2 new triple stellar systems, as well as 2279 point-like sources. We used Monte Carlo simulations and the Bayesian theorem to determine that 1.05(-0.70)(+2.80)% of stars harbor at least one giant planet between 0.5 and 14 MJ and between 20 and 300AU. This result is obtained assuming uniform distributions of planet masses and semi-major axes. If we consider power law distributions as measured for close-in planets instead, the derived frequency is 2.30(-1.55)(+5.95)%, recalling the strong impact of assumptions on Monte Carlo output distributions. We also find no evidence that the derived frequency depends on the mass of the hosting star, whereas it does for close-in planets. Conclusions. The international deep planet survey provides a database of confirmed background sources that may be useful for other exoplanet direct imaging surveys. It also puts new constraints on the number of stars with at least one giant planet reducing by a factor of two the frequencies derived by almost all previous works.
99

Abordagens de análise aplicadas ao 1º movimento da sinfonia nº 3, de Gustav Malher /

Mannis, Guilherme Daniel Breternitz. January 2006 (has links)
Orientador: Edson Sekeff Zampronha / Banca: Martha Herr / Banca: John Boudler / Resumo: O presente trabalho de mestrado tem como seu principal objetivo demonstrar que a aplicação de diferentes métodos analíticos a uma mesma obra e sua posterior comparação é uma metodologia eficaz para o estudo da linguagem musical, em particular de uma obra específica e que, através deste procedimento, informações de interesse teórico e interpretativo, que vão além da aplicação isolada de cada método, podem ser alcançadas. Para tanto, foi feita a análise de um movimento de grande duração inserido em uma obra extensa, composta pelo austríaco Gustav Mahler (1860-1911): a Sinfonia nº3. Sobre esta obra foram realizadas três análises: formal segundo Schoenberg e Rosen; motívica, segundo Réti; e schenkeriana, segundo Salzer.Os métodos foram comparados entre si, de modo a identificarem-se as convergências e divergências entre eles; com base nas divergências e convergências, foramindicadas possibilidades de leitura da obra. Ao final, estes resultados foram confrontados com gravações realizadas por grandes orquestras, tendo à frente regentes reconhecidos como grandes intérpretes da obra de Mahler, verifinco como foram solucionados os problemas de divergência analítica e observando, ainda, se as convergências podem ser confirmadas em suas interpretações. / Abstract: The present Master's Degree dissertation seeks to demonstrate that the utilization of different analytical methods to a single opus, and their posterior comparation, in an efficient method for the study of musical language, particularly of an specific opus, and that, through this procedure, information on theoretical and interpretative interest that go beyond the isolated utilization of each method can be reached. Therefore, three analysis of the first movement of Gustav Mahler's 3rd Symphony were made. The three analysis were; formal, according to Schoenberg and Rosen; motivic according to Réti; and schenkerian, according to Salzer. The methods were compared to each other so it would be possible to identify similarities and differences amont them. Then, based on these similarities and differences, possibilities of reading of the work were indicated. In the end, these results were confronted with recording made by great orchestras, conducted by great maestros well-known as great interpreters of Mahler's opus, verifying how the problems of analytical diffrences were resolved and observing as well if the similarities coud be confirmed in their interpretations. / Mestre
100

Contribuições à sistemática e distribuição preditiva dos roedores Juliomys (Cricetidea, Sigmodontinae)

Sarti, Paulo Tomasi 26 February 2016 (has links)
Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2016-05-18T16:45:01Z No. of bitstreams: 1 Paulo Tomasi Sarti_.pdf: 4227574 bytes, checksum: 4e92a5663649351d5cb26a94afe7ea81 (MD5) / Made available in DSpace on 2016-05-18T16:45:01Z (GMT). No. of bitstreams: 1 Paulo Tomasi Sarti_.pdf: 4227574 bytes, checksum: 4e92a5663649351d5cb26a94afe7ea81 (MD5) Previous issue date: 2016-02-26 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / FAPERGS - Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul / Os roedores Juliomys possuem tamanho diminuto e hábito arborícola. Desde seu estabelecimento no ano 2000, o gênero vem sendo estudado e novas informações tem sido apresentadas. Entretanto, devido ao pequeno intervalo de tempo desde então, muitas perguntas ainda esperam por respostas acerca da biologia geral, relações ecológicas, distribuição geográfica, riqueza de espécies e posição filogenética dentro dos Sigmodontinae. Especificamente, estudos morfométricos e genéticos são ferramentas importantes a serem exploradas. O objetivo geral deste estudo foi analisar a morfologia bem como os marcadores genéticos, a fim de subsidiar dados relevantes para a sistemática e biogeografia das espécies de Juliomys. Utilizamos métodos de análise morfológica, morfométrica e molecular para a definição do novo táxon, que conta com alto suporte. Produzimos mapas de potencial ocorrência das espécies de acordo com o as preferências ambientais. Testamos também o monofiletismo do gênero dentro de Sigmodontinae através do estudo de um marcador molecular. Assim, corroborando os estudos anteriores, descrevemos e propomos uma nova espécie para o gênero. Já a modelagem de distribuição das espécies revelou padrões interessantes, com distribuições desiguais ao longo do bioma Mata Atlântica. Evidenciamos ainda que Juliomys trata-se de um clado monofilético, apesar das diferenças morfológicas; dados fundamentais no embasamento de abordagens de distribuição. Ressaltamos que coleções de história natural ou coleções de Museu são fontes essenciais de informações da fauna, pois foram imprescindíveis neste estudo. A conservação da fauna toma os pressupostos da sistemática e biogeografia, como os aqui apresentados, para alicerçar suas ações. / The Juliomys are small-sized arboreal rodents. Since its establishment in 2000, the genus has been studied, and new information has been presented progressively. However, due to the short time period, many questions are still awaiting for answers related about general biology, ecological relationships, geographic distribution, species richness, and phylogenetic position within the Sigmodontinae. Morphometric and genetic studies are important tools to explore these lines. The aim of this study was to analyze the morphology and the genetic markers in order to subsidize the systematic and biogeography of Juliomys species. We use methods of morphologic, morphometric, and molecular analyses to define the new taxon. We produce maps of potential occurrence of the species according to the environmental preferences. Finally, we tested the monophyly of the genus within Sigmodontinae through the study of a molecular marker. Corroborating previous studies, we describe and propose a new species for the genus. The species distribution modeling revealed interesting patterns with unequal distributions along the Atlantic Forest biome. We endorse that Juliomys it is a monophyletic clade, despite the morphological differences. Studies grounded phylogenetically as well as monophyletic clades should be based delivery approaches. It is notorious that natural history museum collections are essential sources of wildlife information, which was crucial to this study. The conservation of fauna takes the systematic and biogeography assumptions, as those presented in this study, to underpin their actions.

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