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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.
171

The use of evolutionary information in protein alignments and homology identification

Ohlson, Tomas January 2006 (has links)
<p>For the vast majority of proteins no experimental information about the three-dimensional structure is known, but only its sequence. Therefore, the easiest way to obtain some understanding of the structure and function of these proteins is by relating them to well studied proteins. This can be done by searching for homologous proteins. It is easy to identify a homologous sequence if the sequence identity is above 30%. However, if the sequence identity drops below 30% then more sophisticated methods have to be used. These methods often use evolutionary information about the sequences, which makes it possible to identify homologous sequences with a low sequence identity.</p><p>In order to build a three--dimensional model from the sequence based on a protein structure the two sequences have to be aligned. Here the aligned residues serve as a first approximation of the structure.</p><p>This thesis focuses on the development of fold recognition and alignment methods based on evolutionary information. The use of evolutionary information for both query and target proteins was shown to improve both recognition and alignments. In a benchmark of profile--profile methods it was shown that the probabilistic methods were best, although the difference between several of the methods was quite small once optimal gap-penalties were used. An artificial neural network based alignment method ProfNet was shown to be at least as good as the best profile--profile method, and by adding information from a self-organising map and predicted secondary structure we were able to further improve ProfNet.</p>
172

Den avgörande uppfattningen : En kvalitativ studie av konsumenters uppfattningar av åtta svenska modeföretag

Danielsson, Micela, Åhs, Frida January 2008 (has links)
<p>Title: The decisive opinion - A qualitative study of consumers opinions of eight Swedish fashion companies.</p><p>Seminar date: 2008-01-14</p><p>Course: Candidate thesis media and communication, 15 ECTS,</p><p>Authors: Micela Danielsson, Frida Åhs</p><p>Advisor: Larsåke Larsson</p><p>Five keywords: Profile, Image, Brand, Fashion and Advertising</p><p>Purpose: The purpose with this study is to evaluate and discuss the connection between profile and the companies’ image in the eye of the consumer.</p><p>Methodology: A qualitative method has been used in the paper, focusgruops interview with respondents from Örebro.</p><p>Theoretical perspectives: The overall theory of the paper is describing fashion theory. profile, identity and image and advertising.</p><p>Empirical foundation: Consumers from Örebro have made a contribution to the basis of our empirical study.</p><p>Conclusions: The results show that fashion and clothes play a big part for the consumers and they ascribe it the part as a way to show their identity, image and express them selves. For none of the companies profile and image did not have a full connection, but a lot of times there were parts of the profile and image that had a connection. The questioned states that they get their opinions from merchandise, stores, store employees and different kinds of advertising. The respondents situation as students had an effect on their opinions, primarily because of their economical situation. They also had a larger opinion of the fashion companies that are larger fashion chains than the companies that represented the smaller ones and the questioned stated that it could depend on that the larger fashion chains focused more on a wider market than the smaller ones. The result showed also that different communication strategies that the respondents primarily noticed were TV-commercials but also other forms of advertising.</p>
173

Code Profiling : Static Code Analysis

Borchert, Thomas January 2008 (has links)
<p>Capturing the quality of software and detecting sections for further scrutiny within are of high interest for industry as well as for education. Project managers request quality reports in order to evaluate the current status and to initiate appropriate improvement actions and teachers feel the need of detecting students which need extra attention and help in certain programming aspects. By means of software measurement software characteristics can be quantified and the produced measures analyzed to gain an understanding about the underlying software quality.</p><p>In this study, the technique of code profiling (being the activity of creating a summary of distinctive characteristics of software code) was inspected, formulized and conducted by means of a sample group of 19 industry and 37 student programs. When software projects are analyzed by means of software measurements, a considerable amount of data is produced. The task is to organize the data and draw meaningful information from the measures produced, quickly and without high expenses.</p><p>The results of this study indicated that code profiling can be a useful technique for quick program comparisons and continuous quality observations with several application scenarios in both industry and education.</p>
174

A disease classifier for metabolic profiles based on metabolic pathway knowledge

Eastman, Thomas 06 1900 (has links)
This thesis presents Pathway Informed Analysis (PIA), a classification method for predicting disease states (diagnosis) from metabolic profile measurements that incorporates biological knowledge in the form of metabolic pathways. A metabolic pathway describes a set of chemical reactions that perform a specific biological function. A significant amount of biological knowledge produced by efforts to identify and understand these pathways is formalized in readily accessible databases such as the Kyoto Encyclopedia of Genes and Genomes. PIA uses metabolic pathways to identify relationships among the metabolite concentrations that are measured by a metabolic profile. Specifically, PIA assumes that the class-conditional metabolite concentrations (diseased vs. healthy, respectively) follow multivariate normal distributions. It further assumes that conditional independence statements about these distributions derived from the pathways relate the concentrations of the metabolites to each other. The two assumptions allow for a natural representation of the class-conditional distributions using a type of probabilistic graphical model called a Gaussian Markov Random Field. PIA efficiently estimates the parameters defining these distributions from example patients to produce a classifier. It classifies an undiagnosed patient by evaluating both models to determine the most probable class given their metabolic profile. We apply PIA to a data set of cancer patients to diagnose those with a muscle wasting disease called cachexia. Standard machine learning algorithms such as Naive Bayes, Tree-augmented Naive Bayes, Support Vector Machines and C4.5 are used to evaluate the performance of PIA. The overall classification accuracy of PIA is better than these algorithms on this data set but the difference is not statistically significant. We also apply PIA to several other classification tasks. Some involve predicting various manipulations of the metabolic processes performed in experiments with worms. Other tasks are to classify pigs according to properties of their dietary intake. The accuracy of PIA at these tasks is not significantly better than the standard algorithms.
175

Deformation Study of Nanocrystalline Ni-Fe Alloy using Synchrotron Diffraction

Li, Li 01 August 2010 (has links)
This dissertation addresses two critical issues in the deformation of nc metals and alloys: (1) A stress-induced genuine grain growth after the plastic deformation rather than just a change of the grain shape; (2) A systematically quantitative study of micrsostructural evolution during the plastic deformation. These two critical issues point to the deformation of nc materials with the average-grain sizes within the range of 10 to 50 nm, which is the most interesting and controversial region in the current time. The current study provides a systematic and detailed microstructural evolution for this region, which is definitely beneficial for the investigation of the deformation mechanism in this region, especially for the simulation. The main experimental and data-analysis methods employed in this research are synchrotron high-energy X-ray diffraction, X-ray line profile analysis, and texture analysis. The combination of these methods is beneficial to the accurate microstructural interpretation of the bulk materials.
176

Metabolomics /

Norris, Teresa Emilea January 2006 (has links) (PDF)
Thesis (M.S.)--University of North Carolina at Wilmington, 2006. / Includes bibliographical references (leaf: 26)
177

On approximate likelihood in survival models

Läuter, Henning January 2006 (has links)
We give a common frame for different estimates in survival models. For models with nuisance parameters we approximate the profile likelihood and find estimates especially for the proportional hazard model.
178

The Modulating Effect of Fatty Acids on the Lipid Profile in Colon Epithelial Mucosa In Vivo.

Abrahams, Celeste H. January 2009 (has links)
<p>Several abnormal conditions, including some cancers, have been associated with changes in the membrane lipid and FA composition. Dietary fat serves as a major source of lipids and FA, particularly the polyunsaturated fatty acids (PUFA), n-6 and n-3. High intakes of n-6 PUFA have been linked to the development of colon cancer in association with low n-3 PUFA intake. Therefore understanding the differences in the lipid and FA profiles between cancer and normal cells in the colon, and the role diet plays in these factors may be invaluable in understanding their role in carcinogenesis. This study compares the lipid profile of azoxymethane (AOM) induced colon polyps to that of the surrounding mucosa tissue in rats fed a diet high in n-6 PUFA. Male Fischer rats were fed the AIN-76A diet containing sunflower oil that has high n-6 PUFA content for a period of nine months. Results indicate that the lipid and FA content of the colon polyps differs significantly from the surrounding mucosa. Colon polyps had an increase in membrane phopholipids phosphatidylcholine (PC) and phosphatidylethanolamine (PE). Changes in membrane fluidity were indicated by the decrease (p&lt / 0.05) in the PC/PE and cholesterol/phospholipids (chol/PL) ratios, and increase (p&lt / 0.05) in the polyunsaturated FA/saturated FA (P/S) ratio. Metabolism of FA was significantly altered in the polyps favouring n-6 FA metabolism and the production of prostaglandin E2. No clear indication of impaired &Delta / 6-desauturase enzyme activity was noticed. Increases in the n-6 PUFA content could be a reflection of the dietary FA intake that increases FA incorporation in the polyps. Changes in the FA parameters of the polyps, particularly an increase in C20:4n-6 and the n6/n3 ratio have been shown to contribute to the rapid growth of cancer tissue. These lipid changes associated with the development of colon polyps could provide unique targets for developing strategies in chemoprevention by dietary manipulation.</p>
179

The use of evolutionary information in protein alignments and homology identification

Ohlson, Tomas January 2006 (has links)
For the vast majority of proteins no experimental information about the three-dimensional structure is known, but only its sequence. Therefore, the easiest way to obtain some understanding of the structure and function of these proteins is by relating them to well studied proteins. This can be done by searching for homologous proteins. It is easy to identify a homologous sequence if the sequence identity is above 30%. However, if the sequence identity drops below 30% then more sophisticated methods have to be used. These methods often use evolutionary information about the sequences, which makes it possible to identify homologous sequences with a low sequence identity. In order to build a three--dimensional model from the sequence based on a protein structure the two sequences have to be aligned. Here the aligned residues serve as a first approximation of the structure. This thesis focuses on the development of fold recognition and alignment methods based on evolutionary information. The use of evolutionary information for both query and target proteins was shown to improve both recognition and alignments. In a benchmark of profile--profile methods it was shown that the probabilistic methods were best, although the difference between several of the methods was quite small once optimal gap-penalties were used. An artificial neural network based alignment method ProfNet was shown to be at least as good as the best profile--profile method, and by adding information from a self-organising map and predicted secondary structure we were able to further improve ProfNet.
180

Den avgörande uppfattningen : En kvalitativ studie av konsumenters uppfattningar av åtta svenska modeföretag

Danielsson, Micela, Åhs, Frida January 2008 (has links)
Title: The decisive opinion - A qualitative study of consumers opinions of eight Swedish fashion companies. Seminar date: 2008-01-14 Course: Candidate thesis media and communication, 15 ECTS, Authors: Micela Danielsson, Frida Åhs Advisor: Larsåke Larsson Five keywords: Profile, Image, Brand, Fashion and Advertising Purpose: The purpose with this study is to evaluate and discuss the connection between profile and the companies’ image in the eye of the consumer. Methodology: A qualitative method has been used in the paper, focusgruops interview with respondents from Örebro. Theoretical perspectives: The overall theory of the paper is describing fashion theory. profile, identity and image and advertising. Empirical foundation: Consumers from Örebro have made a contribution to the basis of our empirical study. Conclusions: The results show that fashion and clothes play a big part for the consumers and they ascribe it the part as a way to show their identity, image and express them selves. For none of the companies profile and image did not have a full connection, but a lot of times there were parts of the profile and image that had a connection. The questioned states that they get their opinions from merchandise, stores, store employees and different kinds of advertising. The respondents situation as students had an effect on their opinions, primarily because of their economical situation. They also had a larger opinion of the fashion companies that are larger fashion chains than the companies that represented the smaller ones and the questioned stated that it could depend on that the larger fashion chains focused more on a wider market than the smaller ones. The result showed also that different communication strategies that the respondents primarily noticed were TV-commercials but also other forms of advertising.

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