Didžiuliai informacijos kiekiai yra sukaupiami kiekvieną dieną pasaulyje bei jie sparčiai auga. Apytiksliai duomenų tyrybos algoritmai yra labai svarbūs analizuojant tokius didelius duomenų kiekius, nes algoritmų greitis yra ypač svarbus daugelyje sričių, tuo tarpu tikslieji metodai paprastai yra lėti bei naudojami tik uždaviniuose, kuriuose reikalingas tikslus atsakymas. Ši disertacija analizuoja kelias duomenų tyrybos sritis: dažnų sekų paiešką bei vizualizaciją sprendimų priėmimui. Dažnų sekų paieškai buvo pasiūlyti trys nauji apytiksliai metodai, kurie buvo testuojami naudojant tikras bei dirbtinai sugeneruotas duomenų bazes: • Atsitiktinės imties metodas (Random Sampling Method - RSM) formuoja pradinės duomenų bazės atsitiktinę imtį ir nustato dažnas sekas, remiantis atsitiktinės imties analizės rezultatais. Šio metodo privalumas yra teorinis paklaidų tikimybių įvertinimas, naudojantis standartiniais statistiniais metodais. • Daugybinio perskaičiavimo metodas (Multiple Re-sampling Method - MRM) yra RSM metodo patobulinimas, kuris formuoja kelias pradinės duomenų bazės atsitiktines imtis ir taip sumažina paklaidų tikimybes. • Markovo savybe besiremiantis metodas (Markov Property Based Method - MPBM) kelis kartus skaito pradinę duomenų bazę, priklausomai nuo Markovo proceso eilės, bei apskaičiuoja empirinius dažnius remdamasis Markovo savybe. Didelio duomenų kiekio vizualizavimui buvo naudojami pirkėjų internetu elgsenos duomenys, kurie analizuojami naudojant... [toliau žr. visą tekstą] / Huge amounts of digital information are stored in the World today and the amount is increasing by quintillion bytes every day. Approximate data mining algorithms are very important to efficiently deal with such amounts of data due to the computation speed required by various real-world applications, whereas exact data mining methods tend to be slow and are best employed where the precise results are of the highest important. This thesis focuses on several data mining tasks related to analysis of big data: frequent pattern mining and visual representation. For mining frequent patterns in big data, three novel approximate methods are proposed and evaluated on real and artificial databases: • Random Sampling Method (RSM) creates a random sample from the original database and makes assumptions on the frequent and rare sequences based on the analysis results of the random sample. A significant benefit is a theoretical estimate of classification errors made by this method using standard statistical methods. • Multiple Re-sampling Method (MRM) is an improved version of RSM method with a re-sampling strategy that decreases the probability to incorrectly classify the sequences as frequent or rare. • Markov Property Based Method (MPBM) relies upon the Markov property. MPBM requires reading the original database several times (the number equals to the order of the Markov process) and then calculates the empirical frequencies using the Markov property. For visual representation... [to full text]

The recent decade has witnessed great advances in microarray and genotyping technologies which allow genome-wide single nucleotide polymorphism (SNP) data to be captured on a single chip. As a consequence, genome-wide association studies require the development of algorithms capable of manipulating ultra-large-scale SNP datasets. Towards this goal, this thesis proposes two SNP selection methods; the first using Independent Component Analysis (ICA) and the second based on a modified version of Fast Orthogonal Search. The first proposed technique, based on ICA, is a filtering technique; it reduces the number of SNPs in a dataset, without the need for any class labels. The second proposed technique, orthogonal search based SNP selection, is a multivariate regression approach; it selects the most informative features in SNP data to accurately model the entire dataset. The proposed methods are evaluated by applying them to publicly available gene SNP datasets, and comparing the accuracies of each method in reconstructing the datasets. In addition, the selection results are compared with those of another SNP selection method based on Principal Component Analysis (PCA), which was also applied to the same datasets. The results demonstrate the ability of orthogonal search to capture a higher amount of information than ICA SNP selection approach, all while using a smaller number of SNPs. Furthermore, SNP reconstruction accuracies using the proposed ICA methodology demonstrated the ability to summarize a greater or equivalent amount of information in comparison with the amount of information captured by the PCA-based technique reported in the literature. The execution time of the second developed methodology, mFOS, has paved the way for its application to large-scale genome wide datasets. / Thesis (Master, Computing) -- Queen's University, 2010-12-15 18:03:00.208

Nanoparticles, i.e. particles with at least one dimension smaller than 100 nm, are present in large quantities in ambient air and can also be found in an increasing amount of consumer products. It is known that many nanomaterials have physicochemical properties that differ from physicochemical properties of the same material in bulk size. It is therefore important to characterize nanoparticles and to evaluate their toxicity. To understand mechanisms behind nanotoxicity, it is important to study the uptake of nanoparticles, and how they are accumulated. For these purposes model studies of cellular uptake are useful. In this thesis metal oxide and carbon-based nanoparticles have been studied in living cells using Raman spectroscopy. Raman spectroscopy is a method that facilitates a non-destructive analysis without using any fluorescent labels, or any other specific sample preparation. It is possible to collect Raman images, i.e. images where each pixel corresponds to a Raman spectrum, and to use the spectral information to detect nanoparticles, and to identify organelles in cells. In this thesis the question whether or not nanoparticles can enter the cell nucleus of lung epithelial cells has been addressed using hyperspectral analysis. It is shown that titanium dioxide nanoparticles and iron oxide nanoparticles are taken up by cells, and also in the cell nucleus. In contrast, graphene oxide nanoparticles are mainly found attached on the outside of the cell membrane and very few nanoparticles are found in the cell, and none have been detected in the nucleus. It is concluded that graphene oxide nanoparticles are not cytotoxic. However, a comparison of Raman spectra of biomolecules in cells exposed to graphene oxide, unexposed cells and apoptotic cells, shows that the graphene oxide nanoparticles do affect lipid and protein structures. In this thesis, several multivariate data analysis methods have been used to analyze Raman spectra and Raman images. In addition, super-resolution algorithms, which originally have been developed to improve the resolution in photographic images, were optimized and applied to Raman images of cells exposed to submicron polystyrene particles in living cells.

This paper examines the development of income in the tourist generating coun-tries, the relative prices controlled for the exchange rate, and the distance in kilo-meters between the capital in the origin countries and Athens as determinants of international tourism demand for Greece. By the deployment of an OLS log-linear regression model coupled with annual cross-section data for the period between 1998 and 2007, the desired effects could be captured. The results from this study indicates that after 2004, both the importance of income in the tourist generating countries and distance between the countries of origin and Athens have expe-rienced a quantum drop in importance as determinants of international tourism demand for Greece. Furthermore, the elasticities of these factors remained at the new level throughout the remaining period studied. This suggests that the respec-tive elasticities have reached a new plateau after 2004 where the impact on inter-national tourism demand is less sensitive to changes in these specific factors. Final-ly, the investments made in infrastructure supporting the Olympic Games have the possibility to benefit the T&T sector in Greece for an extended period of time going forward.

Youth require opportunities to master and demonstrate new skills, make independent choices, and form positive social relationships to encourage positive youth development. Camps provide a unique setting that fosters the development of new sources of social capital and social support. Current literature examining positive youth development in camps has been able to identify some demographic differences in camper experiences at camp, but has not yielded statistically significant relationships and no consensus as to the explanations for those relationships. Using a longitudinal dataset gathered in a camp setting, this study examined the relationships between gender and age and personal development. Social capital and social support were found to have significant roles as mediating variables in the development of personal development at camp. This study enhances the understanding of the benefits to children from attending camp, and why females and older children may benefit the most from these experiences.

This study is about the school teachers’ positions in contemporary Swedish society. In order to grasp the social characteristics of their profession and its transformations it has been important to conduct thorough analyses of the recruitment of teacher students and the recruitment to the teaching professions. The explanations to the findings are mainly based on analyses of how different kinds of assets – such as for example cultural capital and educational capital – are distributed among the students and within the school teacher corps. The data material consists of individual based statistic of all teachers 1978–2008 and all students enrolled in higher education 1977–2009, and of interviews with teachers and students. Regarding theory and methods, the study belongs to the sociological tradition founded by Pierre Bourdieu, which means that capital, strategies and social space are key concepts. The statistical techniques employed comprise mainly of different variants of correspondence analysis as well as logistic regression. As shown in the first part of the thesis an increasing share of the teacher students possess small amounts of acquired school capital, as well as weak resources inherited from their parental home. This change has been especially noticeable within the programmes educating upper secondary school teachers. In the second part, the focus is on the social positions of those upper secondary teachers. The correspondence analyses indicate a cleavage within the profession based on the teachers’ qualification and merits. Teachers richer in educational capital tend to occupy more stable professional positions and are also overrepresented at schools where the pupils feature significant educational and social assets, which in turn further contributes to the density of educational capital. One of the main results is that school teachers have been exposed to two partly opposing processes during the past decades. On the one hand, there has been increasing homogeneity, namely convergences between the employment conditions of different categories of school teachers and between different teacher education programmes. On the other hand, the social divergences within the profession tend to widen. Those gaps have increased over time because of the more differentiated school system and changes in recruitment patterns.

The purpose of this research is to reduce maintenance resources and improve Escravos–Gas–to–Liquids plant availability (EGTL) in Escravos, Nigeria using wireless condition monitoring. Secondary to the above is to justify the use of this technology over other conventional condition monitoring methods in petrochemical plants with specific reference to cost, reliability and security of the system. Wireless and continuous condition monitoring provides the means to evaluate current conditions of equipment and detect abnormalities. It allows for corrective measures to be taken to prevent upcoming failures. Continuous monitoring and event recording provides information on the energized equipment's response to normal and emergency conditions. Wireless/remote monitoring helps to coordinate equipment specifications and ratings, determine the real limits of the monitored equipment and optimize facility operations. Bentley N, (2005). Using wireless techniques eliminate any need for special cables and wires with lower installation costs if compared to other types of condition monitoring systems. In addition to this, wireless condition monitoring works well under difficult conditions in strategically important locations. The Escravos gas–to–liquid plant in Nigeria, located in a remote and offshore area where accommodation and space for offices is a factor for monitoring plant conditions in every office, is a typical example. Wireless technology for condition monitoring of energized equipment is applicable to both standalone and remote systems. In the research work of Meyer and Brambley (2002), they characterized the current problem with regards to cost effectiveness and availability of wireless condition monitoring. Maintenance of rotating equipment provides probability estimates of the total impact of the problem, cost implication of plant equipment maintenance and describes a generic system in which these developing technologies are used to provide real–time wireless/remote condition monitoring for rotating main air compressor (MAC) units and their components as a case study. Costs with today’s technology are provided and future costs are estimated, showing that benefits will greatly exceed costs in many cases, particularly if low–cost wireless monitoring is used. With management trends such as “re–engineering” and “downsizing” of the available workforce, wireless condition–monitoring of critical machines has been given more importance as a way to ensure quality production with fewer personnel. Wireless condition–monitoring using inexpensive wireless communication technology frees up existing plant maintenance personnel work on machines that are signaling problems and focusing the maintenance efforts away from attempting to work on a large population of machines to only those machines requiring immediate attention. Lloyd and Buddy (200) suggested that Point–to–point wireless data transmission systems, an excellent example of recent technological advances in communication systems, are now practical and cost–effective for industrial use. While both complex infrastructures and complex protocols are required for cellular communications, non– cellular communication systems, such as the point–to–point wireless data transmission system example, require no elaborate infrastructure. Limited research was done on the immediate benefits of implementing wireless condition monitoring systems in plants. All papers on the subject have been drawn up by manufacturers of such equipment. This research will thus also deliver a "third–party" perspective on the effectiveness of such devices, justifying their impact on data gathering security, cost and reliability. / Thesis (M.Ing. (Development and Management Engineering))--North-West University, Potchefstroom Campus, 2012.

The sharing of needles among injection drug users (IDUs) is a common route of Human Immunodeficiency Virus and Hepatitis C Virus transmission. Through the increased utilization of social network analysis, researchers have been able to examine how the interpersonal relationships of IDUs affect injection risk behaviour. This study involves a secondary analysis of data from a cross-sectional study of 156 IDUs from Winnipeg, Manitoba titled “Social Network Analysis of Injection Drug Users”. Multiple logistic regression analysis was used to assess the individual and the social network characteristics associated with needle sharing among the IDUs. Generalized Estimating Equations analysis was used to determine the injecting dyad characteristics which influence needle sharing behaviour between the IDUs and their injection drug using network members. The results revealed five key thematic findings that were significantly associated with needle sharing: (1) types of drug use, (2) socio-demographic status, (3) injecting in semi-public locations, (4) intimacy, and (5) social influence. The findings from this study suggest that comprehensive prevention approaches that target individuals and their network relationships may be necessary for sustainable reductions in needle sharing among IDUs.

The purpose of this research is to reduce maintenance resources and improve Escravos–Gas–to–Liquids plant availability (EGTL) in Escravos, Nigeria using wireless condition monitoring. Secondary to the above is to justify the use of this technology over other conventional condition monitoring methods in petrochemical plants with specific reference to cost, reliability and security of the system. Wireless and continuous condition monitoring provides the means to evaluate current conditions of equipment and detect abnormalities. It allows for corrective measures to be taken to prevent upcoming failures. Continuous monitoring and event recording provides information on the energized equipment's response to normal and emergency conditions. Wireless/remote monitoring helps to coordinate equipment specifications and ratings, determine the real limits of the monitored equipment and optimize facility operations. Bentley N, (2005). Using wireless techniques eliminate any need for special cables and wires with lower installation costs if compared to other types of condition monitoring systems. In addition to this, wireless condition monitoring works well under difficult conditions in strategically important locations. The Escravos gas–to–liquid plant in Nigeria, located in a remote and offshore area where accommodation and space for offices is a factor for monitoring plant conditions in every office, is a typical example. Wireless technology for condition monitoring of energized equipment is applicable to both standalone and remote systems. In the research work of Meyer and Brambley (2002), they characterized the current problem with regards to cost effectiveness and availability of wireless condition monitoring. Maintenance of rotating equipment provides probability estimates of the total impact of the problem, cost implication of plant equipment maintenance and describes a generic system in which these developing technologies are used to provide real–time wireless/remote condition monitoring for rotating main air compressor (MAC) units and their components as a case study. Costs with today’s technology are provided and future costs are estimated, showing that benefits will greatly exceed costs in many cases, particularly if low–cost wireless monitoring is used. With management trends such as “re–engineering” and “downsizing” of the available workforce, wireless condition–monitoring of critical machines has been given more importance as a way to ensure quality production with fewer personnel. Wireless condition–monitoring using inexpensive wireless communication technology frees up existing plant maintenance personnel work on machines that are signaling problems and focusing the maintenance efforts away from attempting to work on a large population of machines to only those machines requiring immediate attention. Lloyd and Buddy (200) suggested that Point–to–point wireless data transmission systems, an excellent example of recent technological advances in communication systems, are now practical and cost–effective for industrial use. While both complex infrastructures and complex protocols are required for cellular communications, non– cellular communication systems, such as the point–to–point wireless data transmission system example, require no elaborate infrastructure. Limited research was done on the immediate benefits of implementing wireless condition monitoring systems in plants. All papers on the subject have been drawn up by manufacturers of such equipment. This research will thus also deliver a "third–party" perspective on the effectiveness of such devices, justifying their impact on data gathering security, cost and reliability. / Thesis (M.Ing. (Development and Management Engineering))--North-West University, Potchefstroom Campus, 2012.

The H.E.S.S. array is a third generation Imaging Atmospheric Cherenkov Telescope (IACT) array. It is located in the Khomas Highland in Namibia, and measures very high energy (VHE) gamma-rays. In Phase I, the array started data taking in 2004 with its four identical 13 m telescopes. Since then, H.E.S.S. has emerged as the most successful IACT experiment to date. Among the almost 150 sources of VHE gamma-ray radiation found so far, even the oldest detection, the Crab Nebula, keeps surprising the scientific community with unexplained phenomena such as the recently discovered very energetic flares of high energy gamma-ray radiation. During its most recent flare, which was detected by the Fermi satellite in March 2013, the Crab Nebula was simultaneously observed with the H.E.S.S. array for six nights. The results of the observations will be discussed in detail during the course of this work. During the nights of the flare, the new 24 m × 32 m H.E.S.S. II telescope was still being commissioned, but participated in the data taking for one night. To be able to reconstruct and analyze the data of the H.E.S.S. Phase II array, the algorithms and software used by the H.E.S.S. Phase I array had to be adapted. The most prominent advanced shower reconstruction technique developed by de Naurois and Rolland, the template-based model analysis, compares real shower images taken by the Cherenkov telescope cameras with shower templates obtained using a semi-analytical model. To find the best fitting image, and, therefore, the relevant parameters that describe the air shower best, a pixel-wise log-likelihood fit is done. The adaptation of this advanced shower reconstruction technique to the heterogeneous H.E.S.S. Phase II array for stereo events (i.e. air showers seen by at least two telescopes of any kind), its performance using MonteCarlo simulations as well as its application to real data will be described. / Das H.E.S.S. Experiment misst sehr hochenergetische Gammastrahlung im Khomas Hochland von Namibia. Es ist ein sogenanntes abbildendes atmosphärisches Cherenkov-Teleskopsystem welches in der 1. Phase, die im Jahr 2004 mit der Datennahme begann, aus vier identischen 13 m Spiegelteleskopen bestand. Seitdem hat sich H.E.S.S. als das erfolgreichstes Experiment in der bodengebundenen Gammastrahlungsastronomie etabliert. Selbst die älteste der mittlerweile fast 150 entdeckten Quellen von sehr hochenergetischer Gammastrahlung, der Krebsnebel, fasziniert immernoch Wissenschaftler mit neuen bisher unbekannten und unerwarteten Phänomenen. Ein Beispiel dafür sind die vor kurzem entdeckten sehr energiereichen Ausbrüche von hochenergetischer Gammastrahlung. Bei dem letzten deratigen Ausbruch des Krebsnebels im März 2013 hat das H.E.S.S. Experiment für sechs Nächte simultan mit dem Fermi-Satelliten, welcher den Ausbruch entdeckte, Daten genommen. Die Analyse der Daten, deren Ergebnis und deren Interpretation werden im Detail in dieser Arbeit vorgestellt. Während dieser Beobachtungen befand sich ein neues 24 m × 32 m großes Spiegelteleskop, das H.E.S.S. II- Teleskop, noch in seiner Inbetriebnahme, trotzdem hat es für eine dieser sechs Nächte an der Datennahme des gesamten Teleskopsystems teilgenommen. Um die Daten rekonstruieren und analysieren zu können, mussten die für die 1. Phase des Experiments entwickelten Algorithmen und die Software des H.E.S.S.- Experiments angepasst werden. Die fortschrittlichste Schauerrekonstruktionsmethode, welche von de Naurois und Rolland entwickelt wurde, basiert auf dem Vergleich von echten Schauerbildern, die mit Hilfe der Cherenkov-Kameras der einzelnen Teleskope aufgenommen wurden, mit Schauerschablonen die mit Hilfe eines semianalytischen Modells erzeugt wurden. Das am besten passende Bild und damit auch alle relevanten Schauerparameter, wird mit Hilfe einer pixelweisen Loglikelihood-Anpassung ermittelt. Die nötigen Änderungen um Multiteleskopereignisse, welche vom heterogenen H.E.S.S. Phase II Detektor gemessen wurden, mit Hilfe dieser fortschrittlichen Schauerrekonstruktionsmethode analysieren zu können, sowie die resultierenden Ergebnisse von MonteCarlo-Simulationen, als auch die Anwendung auf echte Daten, werden im Rahmen dieser Arbeit präsentiert.