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Showing 91 to 99 of 99 (0.055 seconds)Spelling suggestions: "subject:"attern 2analysis"" "subject:"attern 3analysis""
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Untersuchungen zur Variabilität der Ausbildung hyperdermaler Wasserspeichergewebe unter Berücksichtigung variegater PeriklinalchimärenFaßmann, Natalie 09 June 2008 (has links)
Die Arbeit ist in drei Teile untergliedert: Die Struktur "Hypodermales Wasserspeichergewebe" wird unter anatomischen, ökomorphologischen und evolutionsbiologischen Gesichtspunkten betrachtet. Die Anwesenheit eines farblosen Hypoderms erschwert bei der Musteranalyse variegater Periklinalchimären die Bestimmung der Konstitution der L2. Variegate Periklinalchimären mit Hypodermbildung wurden auf die Möglichkeiten der Bestimmung der L2 hin untersucht. Es werden verschiedene Entstehungsformen von maskierenden Mustern und die noch nicht beschriebenen Ringzellen vorgestellt, die den Idiotyp der L2-bürtigen Schicht anzeigen können. Ringzellen sind die Zellen, die im Bereich der Schließzellen an den substomatären Interzellularraum grenzen. Sie bilden dabei einen Ring um die Schließzellen, der im Flächenschnitt zu erkennen ist. Hypodermale Wasserspeichergewebe sind hauptsächlich bei tropischen Arten verbreitet. Die xeromorphe Struktur kommt sowohl bei den epiphytischen Bromelien als auch bei den hygromorphen Schattenpflanzen des tropischen Regenwaldes vor. Die beiden Selektionsfaktoren Trockenheit und Lichtintensität werden als mögliche Einflussfaktoren auf die Hypodermbildung diskutiert. Beispiele dafür, dass der Faktor Licht auch einen modifikativen Einfluss auf die Differenzierung der Hypodermzellen zu haben scheint, werden vorgestellt. Die Struktur "Hypodermales Wasserspeichergewebe" ist sowohl bei Monokotylen als auch Dikotylen gleichermaßen verbreitet. Es wird daher vermutet, dass es sich um eine analoge Struktur handelt, die mehrmals voneinander unabhängig zu verschiedenen Zeiten bei verschiedenen Arten entstanden ist. Innerhalb einer Gruppe verwandter Arten konnte sie mithilfe der Homologiekriterien als homolog eingestuft werden. / This paper contains three different issues: The structure "hypodermal water storage tissue" is considered from the anatomical, the ecomorphological and evolutionary aspect. Because hypodermal layers are non-green, it is difficult to make a pattern analysis of variegated periclinal chimeras and to determine the constitution of L2. Variegated periclinal chimeras with hypodermal layers were examined to the possibilities of determining L2. Different origins of masking patterns and the non-yet described ring cells are presented. Both structures are able to show the L2-genotype. Ring cells are those cells bordering the intercellular space near the stomata. In a cut parallel to the surface the ring built by ring cells is seen. The hypodermal water storage tissue is mainly distributed among tropical species. The xeromorphic structure occurs both to the epiphytic bromeliads and to the hygromorphic shadow plants of the tropical rainforest. The environmental factors humidity and solar radiation are discussed as possible influences on the development of hypodermal layers. Examples for the apparent modifying influence of solar radiation on the development of hypodermal cells are presented. The structure "hypodermal water storage tissue" occurs both to monocots and dicots. That indicates that it is an analogues structure and that it evolved several times independent of each other in different species. Among a group of nearly related species it could be classified by the aid of the criteria of homology as a homologues structure.
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n-TARP: A Random Projection based Method for Supervised and Unsupervised Machine Learning in High-dimensions with Application to Educational Data AnalysisYellamraju Tarun (6630578) 11 June 2019 (has links)
Analyzing the structure of a dataset is a challenging problem in high-dimensions as the volume of the space increases at an exponential rate and typically, data becomes sparse in this high-dimensional space. This poses a significant challenge to machine learning methods which rely on exploiting structures underlying data to make meaningful inferences. This dissertation proposes the <i>n</i>-TARP method as a building block for high-dimensional data analysis, in both supervised and unsupervised scenarios.<div><br></div><div>The basic element, <i>n</i>-TARP, consists of a random projection framework to transform high-dimensional data to one-dimensional data in a manner that yields point separations in the projected space. The point separation can be tuned to reflect classes in supervised scenarios and clusters in unsupervised scenarios. The <i>n</i>-TARP method finds linear separations in high-dimensional data. This basic unit can be used repeatedly to find a variety of structures. It can be arranged in a hierarchical structure like a tree, which increases the model complexity, flexibility and discriminating power. Feature space extensions combined with <i>n</i>-TARP can also be used to investigate non-linear separations in high-dimensional data.<br></div><div><br></div><div>The application of <i>n</i>-TARP to both supervised and unsupervised problems is investigated in this dissertation. In the supervised scenario, a sequence of <i>n</i>-TARP based classifiers with increasing complexity is considered. The point separations are measured by classification metrics like accuracy, Gini impurity or entropy. The performance of these classifiers on image classification tasks is studied. This study provides an interesting insight into the working of classification methods. The sequence of <i>n</i>-TARP classifiers yields benchmark curves that put in context the accuracy and complexity of other classification methods for a given dataset. The benchmark curves are parameterized by classification error and computational cost to define a benchmarking plane. This framework splits this plane into regions of "positive-gain" and "negative-gain" which provide context for the performance and effectiveness of other classification methods. The asymptotes of benchmark curves are shown to be optimal (i.e. at Bayes Error) in some cases (Theorem 2.5.2).<br></div><div><br></div><div>In the unsupervised scenario, the <i>n</i>-TARP method highlights the existence of many different clustering structures in a dataset. However, not all structures present are statistically meaningful. This issue is amplified when the dataset is small, as random events may yield sample sets that exhibit separations that are not present in the distribution of the data. Thus, statistical validation is an important step in data analysis, especially in high-dimensions. However, in order to statistically validate results, often an exponentially increasing number of data samples are required as the dimensions increase. The proposed <i>n</i>-TARP method circumvents this challenge by evaluating statistical significance in the one-dimensional space of data projections. The <i>n</i>-TARP framework also results in several different statistically valid instances of point separation into clusters, as opposed to a unique "best" separation, which leads to a distribution of clusters induced by the random projection process.<br></div><div><br></div><div>The distributions of clusters resulting from <i>n</i>-TARP are studied. This dissertation focuses on small sample high-dimensional problems. A large number of distinct clusters are found, which are statistically validated. The distribution of clusters is studied as the dimensionality of the problem evolves through the extension of the feature space using monomial terms of increasing degree in the original features, which corresponds to investigating non-linear point separations in the projection space.<br></div><div><br></div><div>A statistical framework is introduced to detect patterns of dependence between the clusters formed with the features (predictors) and a chosen outcome (response) in the data that is not used by the clustering method. This framework is designed to detect the existence of a relationship between the predictors and response. This framework can also serve as an alternative cluster validation tool.<br></div><div><br></div><div>The concepts and methods developed in this dissertation are applied to a real world data analysis problem in Engineering Education. Specifically, engineering students' Habits of Mind are analyzed. The data at hand is qualitative, in the form of text, equations and figures. To use the <i>n</i>-TARP based analysis method, the source data must be transformed into quantitative data (vectors). This is done by modeling it as a random process based on the theoretical framework defined by a rubric. Since the number of students is small, this problem falls into the small sample high-dimensions scenario. The <i>n</i>-TARP clustering method is used to find groups within this data in a statistically valid manner. The resulting clusters are analyzed in the context of education to determine what is represented by the identified clusters. The dependence of student performance indicators like the course grade on the clusters formed with <i>n</i>-TARP are studied in the pattern dependence framework, and the observed effect is statistically validated. The data obtained suggests the presence of a large variety of different patterns of Habits of Mind among students, many of which are associated with significant grade differences. In particular, the course grade is found to be dependent on at least two Habits of Mind: "computation and estimation" and "values and attitudes."<br></div>
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Sources of dioxins and other POPs to the marine environment : Identification and apportionment using pattern analysis and receptor modelingSundqvist, Kristina January 2009 (has links)
In the studies underlying this thesis, various source tracing techniques were applied to environmental samples from the Baltic region. Comprehensive sampling and analysis of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in surface sediments in Swedish coastal and offshore areas resulted in a unique data set for this region. Nearly 150 samples of surface sediments were analyzed for all tetra- to octa-chlorinated PCDD/Fs. The levels showed large spatial variability with hotspots in several coastal regions. Neither Sweden nor the EU has introduced guideline values for PCDD/Fs in sediment, but comparisons to available guidelines and quality standards from other countries indicate that large areas of primarily coastal sediments may constitute a risk to marine organisms. Multivariate pattern analysis techniques and receptor models, such as Principal Component Analysis (PCA) and Positive Matrix Factorization (PMF), were used to trace sources. These analyses suggested that three to six source types can explain most of the observed pattern variations found in the sediment samples. Atmospheric deposition was suggested as the most important source to offshore areas, thus confirming earlier estimates. However, spatial differences indicated a larger fraction of local/regional atmospheric sources, characterized by PCDFs, in the south. This was indicated by the identification of several patterns of atmospheric origin. In coastal areas, the influence of direct emission sources was larger, and among these, chlorophenol used for wood preservation and emissions from pulp/paper production and other wood related industry appeared to be most important. The historic emissions connected to processes involving chemical reactions with chlorine (e.g. pulp bleaching) were found to be of less importance except at some coastal sites. The analysis of PCDD/Fs in Baltic herring also revealed spatial variations in the levels and pollution patterns along the coast. The geographical match against areas with elevated sediment levels indicated that transfer from sediments via water to organisms was one possible explanation. Fugacity, a concept used to predict the net transport direction between environmental matrices, was used to explore the gas exchange of hexachlorocyclohexanes (HCHs) and polychlorinated biphenyls (PCBs) between air and water. These estimates suggested that, in the Kattegat Sea, the gaseous exchange of HCHs primarily resulted in net deposition while PCBs were net volatilized under certain environmental conditions. The study also indicated that, while the air concentrations of both PCBs and γ-HCH are mostly dependent upon the origin of the air mass, the fluctuations in α-HCH were primarily influenced by seasonal changes.
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Computational analysis of wide-angle light scattering from single cellsPilarski, Patrick Michael 11 1900 (has links)
The analysis of wide-angle cellular light scattering patterns is a challenging problem. Small changes to the organization, orientation, shape, and optical properties of scatterers and scattering populations can significantly alter their complex two-dimensional scattering signatures. Because of this, it is difficult to find methods that can identify medically relevant cellular properties while remaining robust to experimental noise and sample-to-sample differences. It is an important problem. Recent work has shown that changes to the internal structure of cells---specifically, the distribution and aggregation of organelles---can indicate the progression of a number of common disorders, ranging from cancer to neurodegenerative disease, and can also predict a patient's response to treatments like chemotherapy. However, there is no direct analytical solution to the inverse wide-angle cellular light scattering problem, and available simulation and interpretation methods either rely on restrictive cell models, or are too computationally demanding for routine use.
This dissertation addresses these challenges from a computational vantage point. First, it explores the theoretical limits and optical basis for wide-angle scattering pattern analysis. The result is a rapid new simulation method to generate realistic organelle scattering patterns without the need for computationally challenging or restrictive routines. Pattern analysis, image segmentation, machine learning, and iterative pattern classification methods are then used to identify novel relationships between wide-angle scattering patterns and the distribution of organelles (in this case mitochondria) within a cell. Importantly, this work shows that by parameterizing a scattering image it is possible to extract vital information about cell structure while remaining robust to changes in organelle concentration, effective size, and random placement. The result is a powerful collection of methods to simulate and interpret experimental light scattering signatures. This gives new insight into the theoretical basis for wide-angle cellular light scattering, and facilitates advances in real-time patient care, cell structure prediction, and cell morphology research.
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Computational analysis of wide-angle light scattering from single cellsPilarski, Patrick Michael Unknown Date
No description available.
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On Rules and Methods: Neural Representations of Complex Rule Sets and Related Methodological ContributionsGörgen, Kai 20 November 2019 (has links)
Wo und wie werden komplexe Regelsätze im Gehirn repräsentiert? Drei empirische Studien dieser Doktorarbeit untersuchen dies experimentell. Eine weitere methodische Studie liefert Beiträge zur Weiterentwicklung der genutzten empirischen Methode. Die empirischen Studien nutzen multivariate Musteranalyse (MVPA) funktioneller Magnetresonanzdaten (fMRT) gesunder Probanden. Die Fragestellungen der methodischen Studie wurden durch die empirischen Arbeiten inspiriert. Wirkung und Anwendungsbreite der entwickelten Methode gehen jedoch über die Anwendung in den empirischen Studien dieser Arbeit hinaus.
Die empirischen Studien bearbeiten Fragen wie: Wo werden Hinweisreize und Regeln repräsentiert, und sind deren Repräsentationen voneinander unabhängig? Wo werden Regeln repräsentiert, die aus mehreren Einzelregeln bestehen, und sind Repräsentationen der zusammengesetzten Regeln Kombinationen der Repräsentationen der Einzelregeln? Wo sind Regeln verschiedener Hierarchieebenen repräsentiert, und gibt es einen hierarchieabhängigen Gradienten im ventrolateralen präfrontalen Kortex (VLPFK)? Wo wird die Reihenfolge der Regelausführung repräsentiert? Alle empirischen Studien verwenden informationsbasiertes funktionales Mapping ("Searchlight"-Ansatz), zur hirnweiten und räumlich Lokalisierung von Repräsentationen verschiedener Elemente komplexer Regelsätze.
Kernergebnisse der Arbeit beinhalten: Kompositionalität neuronaler Regelrepräsentationen im VLPFK; keine Evidenz für Regelreihenfolgenrepräsentation im VLPFK, welches gegen VLPFK als generelle Task-Set-Kontrollregion spricht; kein Hinweis auf einen hierarchieabhängigen Gradienten im VLPFK.
Die komplementierende methodische Studie präsentiert "The Same Analysis Approach (SAA)", ein Ansatz zur Erkennung und Behebung experimentspezifischer Fehler, besonders solcher, die aus Design–Analyse–Interaktionen entstehen. SAA ist für relevant MVPA, aber auch für anderen Bereichen innerhalb und außerhalb der Neurowissenschaften. / Where and how does the brain represent complex rule sets? This thesis presents a series of three empirical studies that decompose representations of complex rule sets to directly address this question. An additional methodological study investigates the employed analysis method and the experimental design. The empirical studies employ multivariate pattern analysis (MVPA) of functional magnetic resonance imaging (fMRI) data from healthy human participants. The methodological study has been inspired by the empirical work. Its impact and application range, however, extend well beyond the empirical studies of this thesis.
Questions of the empirical studies (Studies 1-3) include: Where are cues and rules represented, and are these represented independently? Where are compound rules (rules consisting of multiple rules) represented, and are these composed from their single rule representations? Where are rules from different hierarchical levels represented, and is there a hierarchy-dependent functional gradient along ventro-lateral prefrontal cortex (VLPFC)? Where is the order of rule-execution represented, and is it represented as a separate higher-level rule? All empirical studies employ information-based functional mapping ("searchlight" approach) to localise representations of rule set features brain-wide and spatially unbiased.
Key findings include: compositional coding of compound rules in VLPFC; no order information in VLPFC, suggesting VLPFC is not a general controller for task set; evidence against the hypothesis of a hierarchy-dependent functional gradient along VLPFC.
The methodological study (Study 4) introduces "The Same Analysis Approach (SAA)". SAA allows to detect, avoid, and eliminate confounds and other errors in experimental design and analysis, especially mistakes caused by malicious experiment-specific design-analysis interactions. SAA is relevant for MVPA, but can also be applied in other fields, both within and outside of neuroscience.
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The crime threat analysis process, an assessmentKrause, André 30 November 2007 (has links)
The study investigated the application of the crime threat analysis process at station level within the Nelson Mandela Metro City area with the objective of determining inhibiting factors (constraints) and best practices.
Qualitative research methodology was applied and interviews were conducted with crime analysts and specialised investigators/intelligence analysts. The research design can be best described as descriptive and explorative in nature.
The crime threat analysis process embroils the application of various crime analysis techniques and the outcomes thereof intends to have a dual purpose of generating operational crime management information in assisting crime prevention initiatives and crime detection efforts, mainly focussing on the criminal activities of group offenders (organised crime related), repeat offenders and serial offenders.
During the study it became evident that crime analysts understand and thus apply the crime threat analysis process indifferently, which impeded on the relevancy and the utilisation thereof as an effective crime management tool. / Criminology / M.Tech. (Policing)
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The crime threat analysis process, an assessmentKrause, André 30 November 2007 (has links)
The study investigated the application of the crime threat analysis process at station level within the Nelson Mandela Metro City area with the objective of determining inhibiting factors (constraints) and best practices.
Qualitative research methodology was applied and interviews were conducted with crime analysts and specialised investigators/intelligence analysts. The research design can be best described as descriptive and explorative in nature.
The crime threat analysis process embroils the application of various crime analysis techniques and the outcomes thereof intends to have a dual purpose of generating operational crime management information in assisting crime prevention initiatives and crime detection efforts, mainly focussing on the criminal activities of group offenders (organised crime related), repeat offenders and serial offenders.
During the study it became evident that crime analysts understand and thus apply the crime threat analysis process indifferently, which impeded on the relevancy and the utilisation thereof as an effective crime management tool. / Criminology and Security Science / M.Tech. (Policing)
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Eine deutschlandweite Potenzialanalyse für die Onshore-Windenergie mittels GIS einschließlich der Bewertung von SiedlungsdistanzenänderungenMasurowski, Frank 11 July 2016 (has links)
Die Windenergie an Land (Onshore-Windenergie) ist neben der Photovoltaik eine der tragenden Säulen der Energiewende in Deutschland. Wie schon in der Vergangenheit
wird auch zukünftig der Ausbau der Onshore-Windenergie, mit dem Ziel eine umweltgerechte
und sichere Energieversorgung für zukünftige Generationen aufzubauen, durch die Politik massiv vorangetrieben. Für eine planvolle Umsetzung der Energiewende, insbesondere im Bereich der Windenergie, müssen Kenntnisse über den zur Verfügung stehenden Raum und der Wirkungsweise standortspezifischer Faktoren auf planungsrechtlicher Ebene vorhanden sein. In der vorliegenden Arbeit wurde die Region Deutschland auf das für dieWindenergie an Land nutzbare Flächenpotenzial analysiert, von diesem allgemein gültige Energiepotenziale abgeleitet und in einer Sensitivitätsanalyse die Einflüsse verschiedener Abstände zwischen den Windenergieanlagen und Siedlungsstrukturen auf das ermittelte Energiepotenzial untersucht. Des
Weiteren wurden für die beobachteten Zusammenhänge zwischen den Distanz- und
Energiepotenzialänderungen mathematische Formeln erstellt, mit deren Hilfe eine Energiepotenzialänderung in Abhängigkeit von spezifischen Siedlungsdistanzänderungen vorhersagbar sind. Die Analyse des Untersuchungsgebiets (USG) hinsichtlich des zur Verfügung stehenden Flächenpotenzials wurde anhand eines theoretischen Modells, welches die reale Landschaft mit ihren unterschiedlichen Landschaftstypen und Infrastrukturen widerspiegelt, umgesetzt. Auf Basis dieses Modells wurden so genannte „Basisflächen“ sowie für die Onshore-Windenergie nicht nutzbare Flächen (Tabu- oder Ausschlussflächen) identifiziert und mittels einer GIS-Software (Geographisches Informationssystem) verschnitten.
Die Identifizierung der Ausschlussflächen erfolgte über regionalisierte beziehungsweise
im gesamten USG geltende multifaktorielle Bestimmungen für die Platzierung von Windenergieanlagen (WEA). Zur Gewährleistung einer einheitlichen Konsistenz wurden die verschiedenen Regelungen, welche aus den unterschiedlichsten Quellen stammen, vereinheitlicht, vereinfacht und in einem so genannten „Regelkatalog“ festgeschrieben. Die Berechnung des im USG maximal möglichen Energiepotenzials erfolgte durch eine Referenzanlage, welche im USG räumlich verteilt platziert wurde. Die Energiepotenziale (Leistungs- und Ertragspotenzial) leiten sich dabei aus der Kombination der räumlichen Lage der WEA, den technischen Leistungsspezifikationen der Referenzanlage und dem regionalem Windangebot ab. Eine wesentliche Grundvoraussetzung für die Berechnung der Energiepotenziale lag in der im Vorfeld durchzuführenden Windenergieanlagenallokation auf den Potenzialflächen begründet. Zu diesem Zweck wurde die integrierte Systemlösung „MAXPLACE“ entwickelt. Mit dieser ist es möglich, WEA unter Berücksichtigung von anlagenspezifischen, wirtschaftlichen und sicherheitstechnischen Aspekten in einzelnen oder zusammenhängenden Untersuchungsregionen zu platzieren. Im Gegensatz zu bereits bestehenden Systemlösungen (Allokationsalgorithmen) aus anderen Windenergie-Potenzialanalysen zeichnet sich die integrierte Systemlösung „MAXPLACE“ durch eine sehr gute Effizienz, ein breites Anwendungsspektrum sowie eine einfache Handhabung aus.
Der Mindestabstand zwischen den WEA und den Siedlungsstrukturen stellt den größten Restriktionsfaktor für das ermittelte Energiepotenzial dar. Zur Bestimmung der Einflussnahme von Siedlungsdistanzänderungen auf das Energiepotenzial wurde mit Hilfe des erstellten Landschaftsmodells eine Sensitivitätsanalyse durchgeführt. In dieser wurden die vorherrschenden Landschafts- und Infrastrukturen analysiert und daraus standortbeschreibende Parameter abgeleitet. Neben der konkreten Benennung der Energiepotenzialänderungen, wurden für das gesamte USG mathematische Abstraktionen der beobachteten Zusammenhänge in Form von Regressionsformeln ermittelt. Diese Formeln ermöglichen es, ohne die in dieser Arbeit beschriebene aufwendige Methodik nachzuvollziehen, mit nur wenigen Parametern die Auswirkungen einer Siedlungsdistanzänderung auf das Energiepotenzial innerhalb des Untersuchungsgebiets zu berechnen.
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