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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.
321

Spectral Line Synthesis for Hot stars

Huang, Wenjin 08 August 2005 (has links)
I developed a spectrum synthesis method to investigate the physical properties of hot OB main sequence (MS) stars, which are often rapid rotators. The code realistically simulates the surface conditions of rapidly rotating stars, considering the rotationally-deformed stellar shape and gravity darkening effect. Comparing the synthesized absorption line profiles with the observed spectra of the member stars of 19 young Galactic clusters, I determined the projected rotational velocities of 496 stars. The average surface temperature and gravity for most of these objects were then derived from H$\gamma$ line fits. The polar gravity of each star was estimated as a good indicator of the evolutionary status of the star. The derived parameters show that massive rotators spin down during their MS phase. The He abundance data (measured by fitting the He I lines) also favor the theoretical prediction that rotationally-induced mixing can gradually enrich the surface helium abundance through the MS phase. A quicker spin-down is evident in the lower mass star group where a large portion of helium peculiar stars are found. This correlation implies that strong stellar magnetic fields may exist on the surface of these lower mass stars. The same method is also applied to interferometric observations from the CHARA Array of a nearby rapid rotator, Regulus. By combining results from spectroscopic and interferometric analysis, the shape, space orientation, mass, and surface temperature distribution of Regulus are firmly determined. This analysis provides the first evidence of the gravity darkening phenomenon among stars that are not components of an eclipsing binary system. The surprisingly high luminosity determined for Regulus appears to agree with the theoretical prediction that rapid rotator can become more luminous as rotationally-induced mixing brings fresh hydrogen down to the core. Finally I present an extension of the model that simulates the shape, velocity, and temperature variations of a star experiencing nonradial pulsation. I simulated and analyzed the line profile variations in the spectra of $\epsilon$ Per, a B0.7~III star with strong evidence of nonradial pulsation (NRP). A comparison of the model simulations and observations indicates that the pulsations of $\epsilon$ Per have a corresponding local temperature variation that is out of phase with the radial oscillation (a non-adiabatic phase lag).
322

COPING STRATEGIES AMONG ELITE SWEDISH FOOTBALL PLAYERS IN RELATION TO THEIR GOAL ORIENTATION PROFILES

Roness, Simon January 2011 (has links)
The objectives of this study were to investigate: (1) elite Swedish football players use of coping strategies, (2) their goal orientations, and (3) the relationship between their goal orientation profiles and use of coping strategies. Participants were 83 male elite Swedish football players. The Perception of Success Questionnaire and COPE inventory were administered to meet the objectives. Results showed a significant interaction effect between athletes’ task and ego goal orientations and their use of planning. Athletes’ with a HT/LE profile (3.06 ± 0.36; M ± SD) used frequently more planning than athletes’ with a LT/LE profile (2.59 ± 0.51). Moreover, athletes’ high in task (2.71 ± 0.37) used more problem-focused strategies than athletes low in task (2.54 ± 0.33), and athletes’ low in ego (2.31 ± 0.24) used more emotion-focused strategies than athletes’ high in ego (2.17 ± 0.27). Results are discussed in relation to previous research of achievement motivation and athletes’ use of coping strategies. / Syftet med föreliggande studie var att undersöka: (1) svenska elitfotbollsspelares användande av coping strategier, (2) deras målorienteringar, och (3) relationen mellan deras målorienteringsprofiler och användande av coping strategier. Urvalet bestod av 83 manliga svenska elitfotbollsspelare. Studiens syften undersöktes med hjälp av The Perception of Success Questionnaire och COPE inventory. Resultaten visade en signifikant interaktionseffekt mellan idrottarnas task och ego orienteringar och användande av planering. Idrottare med en HT/LE profil (3.06 ± 0.36; M ± SD) använde sig av mer planering än idrottare med en LT/LE profil (2.59 ± 0.51). Vidare använde idrottare med en hög task-orientering (2.71 ± 0.37) sig av mer problem-fokuserade strategier än idrottare med en låg task-orientering (2.54 ± 0.33) och idrottare med en låg ego-orientering (2.31 ± 0.24) använde mer emotions-fokuserade strategier än idrottare med en hög ego-orientering (2.17 ± 0.27). Resultaten har diskuterats i relation till tidigare forskning inom prestationsmotivation och idrottares coping strategier.
323

The promise of nitrogen plasma implanted gallium arsenide for band gap engineering

Risch, Marcel 31 March 2008 (has links)
This investigation examines band gap engineering of the GaAsN alloy by means of plasma ion implantation. The strong redshift of the alloy's band gap is suitable for telecommunication applications and thus stimulated much interest in recent years. Nitrogen (N) ion implantation into gallium arsenide (GaAs) results in a thin shallow N-rich layer below the surface. However, the violent implantation process also modifies the concentrations of gallium and arsenide. The core of this thesis is a novel method for prediction of the band gap from the conditions in the processing plasma.<p>The first important variable, the number of implanted ions, is obtained from the Lieberman model for the current during high-voltage Plasma Ion Implantation (PII). A review of the model's assumptions is provided as well as a comprehensive discussion of the implantation which includes error boundaries. The predicted and measured ion currents agree within error boundaries. The number of implanted ions can therefore be obtained from the prediction.<p>The distribution of the implanted ions was subsequently explored by simulations such as TRIM and TRIDYN. It was found that the nitrogen content in GaAs is limited by the sputtering of the surface atoms. Furthermore, the content of gallium increases near the surface while the content of arsenic decreases. The predicted ratios of the constituents in the implanted layer is such that the alloy cannot form by ion implantation alone; it could be reconciled by annealing.<p>Preliminary samples were produced and tested for the formation of the GaAsN alloy by Raman spectroscopy. No evidence for bonds between N and either Ga or As was found in the as-implanted samples. The thesis concludes with a discussion of the necessary steps to synthesize the GaAsN alloy.
324

Security, Privacy, Identity And Patient Consent Management Across Healthcare Enterprises Inintegrated Healthcare Enterprises (ihe) Cross Enterprise Document Sharing (xds) Affinity Domain

Namli, Tuncay 01 June 2007 (has links) (PDF)
Integrated Healthcare Enterprise (IHE) is an initiative by industry and healthcare professionals to improve knowledge sharing and interoperability between healthcare related enterprises. IHE publishes Integration Profiles on several Healthcare Fields to define how systems can use existing standards and technologies to execute a specific use case in healthcare. Cross Enterprise Document Sharing (XDS) is such a profile which defines the way of sharing Electronic Health Records (EHR) between healthcare enterprises. In this thesis, IHE Cross Enterprise User Authentication, IHE Node Authentication and Audit Trail, IHE Basic Patient Privacy Consent profiles are implemented based on the IHE XDSimplementation by National Institute of Standards, USA. Furthermore, some of the unspecified issues related with these profiles are clarified and new techniques are offered for their implementations. One of the contribution of the thesis is to use OASIS Extensible Access Control Markup Language (XACML) to define patient consent policies and manage access control. Other technologies and standards that are used in the implementation are as follows / OASIS Security Assertion Markup Language (SAML), XML Signature, Mutual Transport Layer Security (TLS), RFC 3195 Reliable Delivery for Syslog, RFC 3881 Security Audit and Access Accountability Message XML Data Definitions.
325

Automated Biological Data Acquisition And Integration Using Machine Learning Techniques

Carkacioglu, Levent 01 February 2009 (has links) (PDF)
Since the initial genome sequencing projects along with the recent advances on technology, molecular biology and large scale transcriptome analysis result in data accumulation at a large scale. These data have been provided in different platforms and come from different laboratories therefore, there is a need for compilation and comprehensive analysis. In this thesis, we addressed the automatization of biological data acquisition and integration from these non-uniform data using machine learning techniques. We focused on two different mining studies in the scope of this thesis. In the first study, we worked on characterizing expression patterns of housekeeping genes. We described methodologies to compare measures of housekeeping genes with non-housekeeping genes. In the second study, we proposed a novel framework, bi-k-bi clustering, for finding association rules of gene pairs that can easily operate on large scale and multiple heterogeneous data sets. Results in both studies showed consistency and relatedness with the available literature. Furthermore, our results provided some novel insights waiting to be experimented by the biologists.
326

Time-resolved thermodynamics studies of heme signaling proteins and model systems

Mokdad, Audrey 01 June 2009 (has links)
Heme-based gas sensor proteins have the ability to sense diatomic molecules such as O2 (FixL, EcDos or HemAT), CO (CooA, a CO-sensing protein of Rhodospirillum rubrum) and NO (guanylate cyclase) molecules and subsequently regulate numerous important biological processes in prokaryotic and eukaryotic organisms. The sensing function of these proteins is initiated by the binding of an effector (i.e., O2, CO, etc5) to the heme iron which then leads to a cascade of conformational events which gives rise to changes in kinase activity, DNA-binding activity, etc... In order to better understand the mechanism heme-based signaling, time resolved photothermal methods as well as transient optical techniques were utilized to obtain thermodynamic profiles for ligand binding/release in heme based signaling proteins including HemAT from Bacillus subtilis (aerotactic transducer), FixL from Sinorhizobium meliloti (regulation of the nitrogen fixation) and CooA from Rhodospirillum rubrum (transcriptional activator). In addition, a number of model systems were examined to understand the underlying thermodynamic processes involved in heme ligation. The variation of volume and enthalpy changes associated with spin state change of the iron from high-spin to low-spin where examined using the spin crossover Fe(III)(salten)(mepepy) complex. In addition, the experimental determination of the volume change due to electrostriction events were using Ru(II)(L)3 and the Debye-Hückel equation. Finally, different model heme proteins were studied to understand how a signal is conformationaly transmitted within a heme protein matrix. Sandbar shark hemoglobin was examined as an example of a non-signaling an allosteric protein. Two different peroxidases (horseradish and soybean) which have a direct channel between the heme pocket and the solvent involving no barrier energetic for the photodissociated ligand leaving the heme pocket were examined as example of non-signaling, non-allosteric proteins. The results show that each protein has a unique thermodynamic profile to conformationaly transmit signals subsequent to photodissociation of CO, even within the same class of protein (i.e. PAS domains, globins, etc...).
327

Characterisation of chemical components in manually isolated aleurone and associated layers from maize, wheat and barley kernels

Ndolo, Victoria Uchizi January 2015 (has links)
Health benefits related to consumption of whole grains have been attributed in part to phytochemical and micronutrient composition. Understanding the composition, structure and distribution of these components in different cereal grains is of potential importance in aiding the selection of whole grains and their processed fractions for inclusion in the diet, and as ingredients in development of new food products. The aim of this research was to characterise the chemical components in the botanical fractions of yellow corn, barley, wheat. Manual separation, a tedious and laborious technique that yields pure fractions, suitable for compositional analysis, was used to separate whole grains into pericarp, aleurone layer, germ and endosperm fractions. Component identification and quantification of tissue components was accomplished by several techniques. The study also explored the possibility of using spectral characteristics fluorescence intensity values to provide rapid estimates of the concentrations and distribution of ferulic acid (FA), a major phenolic compound in cereal grains. While composition of phenolic acids and carotenoids was similar, the distribution was significantly different (P < 0.05) among cereal types and grain fractions. Phenolic acids were concentrated in pericarp and aleurone fractions, followed by the germ and the endosperm had the lowest levels. Yellow corn exhibited the highest values. Carotenoids, lutein and zeaxanthin were concentrated in the germ and aleurone layer of wheat and barley while in yellow corn it was in the endosperm and aleurone layer. This is the first study to report on carotenoid composition of aleurone fractions. Mineral elements, thiamine and niacin were higher in wheat aleurone than in purple barley and yellow corn aleurone layers. These findings suggest that yellow corn aleurone layers have potential as a functional food ingredient despite the low micronutrient content. A positive, significant correlation (r= 0.421, p < 0.0001) was found between fluorescence intensity values and ferulic acid concentration. Thus, fluorescence intensity profiles are a promising approach for rapid assessment of FA concentration in grain in-situ. This work has provided information that would act as a database for selection of cereal fractions and guide the miller to obtain grain fractions with enriched levels of phytochemicals and micronutrients. / February 2016
328

Two Novel Methods for Clustering Short Time-Course Gene Expression Profiles

2014 January 1900 (has links)
As genes with similar expression pattern are very likely having the same biological function, cluster analysis becomes an important tool to understand and predict gene functions from gene expression profi les. In many situations, each gene expression profi le only contains a few data points. Directly applying traditional clustering algorithms to such short gene expression profi les does not yield satisfactory results. Developing clustering algorithms for short gene expression profi les is necessary. In this thesis, two novel methods are developed for clustering short gene expression pro files. The fi rst method, called the network-based clustering method, deals with the defect of short gene expression profi les by generating a gene co-expression network using conditional mutual information (CMI), which measures the non-linear relationship between two genes, as well as considering indirect gene relationships in the presence of other genes. The network-based clustering method consists of two steps. A gene co-expression network is firstly constructed from short gene expression profi les using a path consistency algorithm (PCA) based on the CMI between genes. Then, a gene functional module is identi ed in terms of cluster cohesiveness. The network-based clustering method is evaluated on 10 large scale Arabidopsis thaliana short time-course gene expression profi le datasets in terms of gene ontology (GO) enrichment analysis, and compared with an existing method called Clustering with Over-lapping Neighbourhood Expansion (ClusterONE). Gene functional modules identi ed by the network-based clustering method for 10 datasets returns target GO p-values as low as 10-24, whereas the original ClusterONE yields insigni cant results. In order to more speci cally cluster gene expression profi les, a second clustering method, namely the protein-protein interaction (PPI) integrated clustering method, is developed. It is designed for clustering short gene expression profi les by integrating gene expression profi le patterns and curated PPI data. The method consists of the three following steps: (1) generate a number of prede ned profi le patterns according to the number of data points in the profi les and assign each gene to the prede fined profi le to which its expression profi le is the most similar; (2) integrate curated PPI data to refi ne the initial clustering result from (1); (3) combine the similar clusters from (2) to gradually reduce cluster numbers by a hierarchical clustering method. The PPI-integrated clustering method is evaluated on 10 large scale A. thaliana datasets using GO enrichment analysis, and by comparison with an existing method called Short Time-series Expression Miner (STEM). Target gene functional clusters identi ed by the PPI-integrated clustering method for 10 datasets returns GO p-values as low as 10-62, whereas STEM returns GO p-values as low as 10-38. In addition to the method development, obtained clusters by two proposed methods are further analyzed to identify cross-talk genes under fi ve stress conditions in root and shoot tissues. A list of potential abiotic stress tolerant genes are found.
329

The Music of the Stars : Spectroscopy of Pulsations in gamma Doradus Stars

Brunsden, Emily January 2013 (has links)
The mysteries of the interior structures of stars are being tackled with asteroseismology. The observable parameters of the surface pulsations of stars inform us of the interior characteristics of numerous classes of stars. The main-sequence gamma Doradus stars, just a little hotter than the Sun, offer the potential of determining stellar structure right down to the core. To determine the structural profile of a star, the observed frequencies and a full geometric description must be determined. This is only possible with long-term spectroscopic monitoring and careful analysis of the pulsation signature in spectral lines. This work seeks to identify the pulsational geometry of several gamma Doradus stars and to identify areas of improvement for current observation, analysis and modelling techniques. More than 4500 spectra were gathered on five stars for this purpose. For three stars a successful multi-frequency and mode identification solution was determined and significant progress has been made towards the understanding of a binary system involving a gammaDoradus star. A hybrid gamma Doradus/\delta Scuti pulsator was also intensely monitored and results from this work raise important questions about the classification of this type of star. Current analysis techniques were found to be fit-for-purpose for pure gamma Doradus stars, but stars with complexities such as hybrid pulsations and/or fast rotation require future development of the current models.
330

Cab Door Design : Improvement of door corners

Islam, Akib January 2014 (has links)
This thesis presents a product development process, where an existing solution on a cab door have been analysed and developed, with the aim to result in a cost-effective concept solution for handling tolerances on the door frame. The methodological approach in this thesis is based on Volvo Construction Equipment’s development model; The Global Development Process, which started with a pre-study phase where the problem formulation was established. The problem formulation in short is to find a solution for how to handle narrow tolerances in steel profiles for the door weldment on cab doors. Various solution ideas were discussed and concepts were generated with focus to design a new cab door corner that would solve the problems addressed by the project. The applied method resulted in a final concept consisting of the same steel profiles but with new dimensions, and two new concepts in each corner; one corner module that is placed inside the steel profiles and joined by welding, and a plastic shell that covers the welded corner. The concept was validated using a prototype of the proposed solution, where tests show that the requirements were achieved, besides a few deficiencies. A cost comparison between the existing and the proposed solution was made within limitations for this thesis. The result of the cost comparison shows an indication of that the proposed solution can be more cost-effective than the existing solution. Some of the recommendations after have completing the project are to make a complete cost comparison to ensure that the indication is correct and to analyse the new components to optimize and define the dimensions of them.

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