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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.
521

Statistical properties of parasite density estimators in malaria and field applications / Propriétés statistiques des estimateurs de la densité parasitaire dans les études portant sur le paludisme et applications opérationnelles

Hammami, Imen 24 June 2013 (has links)
Pas de résumé en français / Malaria is a devastating global health problem that affected 219 million people and caused 660,000 deaths in 2010. Inaccurate estimation of the level of infection may have adverse clinical and therapeutic implications for patients, and for epidemiological endpoint measurements. The level of infection, expressed as the parasite density (PD), is classically defined as the number of asexual parasites relative to a microliter of blood. Microscopy of Giemsa-stained thick blood smears (TBSs) is the gold standard for parasite enumeration. Parasites are counted in a predetermined number of high-power fields (HPFs) or against a fixed number of leukocytes. PD estimation methods usually involve threshold values; either the number of leukocytes counted or the number of HPFs read. Most of these methods assume that (1) the distribution of the thickness of the TBS, and hence the distribution of parasites and leukocytes within the TBS, is homogeneous; and that (2) parasites and leukocytes are evenly distributed in TBSs, and thus can be modeled through a Poisson-distribution. The violation of these assumptions commonly results in overdispersion. Firstly, we studied the statistical properties (mean error, coefficient of variation, false negative rates) of PD estimators of commonly used threshold-based counting techniques and assessed the influence of the thresholds on the cost-effectiveness of these methods. Secondly, we constituted and published the first dataset on parasite and leukocyte counts per HPF. Two sources of overdispersion in data were investigated: latent heterogeneity and spatial dependence. We accounted for unobserved heterogeneity in data by considering more flexible models that allow for overdispersion. Of particular interest were the negative binomial model (NB) and mixture models. The dependent structure in data was modeled with hidden Markov models (HMMs). We found evidence that assumptions (1) and (2) are inconsistent with parasite and leukocyte distributions. The NB-HMM is the closest model to the unknown distribution that generates the data. Finally, we devised a reduced reading procedure of the PD that aims to a better operational optimization and a practical assessing of the heterogeneity in the distribution of parasites and leukocytes in TBSs. A patent application process has been launched and a prototype development of the counter is in process.
522

Studying biological assembly of ion channel complexes

Moeller, Lena 08 1900 (has links)
Les canaux ioniques sont des complexes macromoléculaires clés exprimés dans tous les types de cellules et sont impliqués dans divers processus physiologiques, y compris la génération et la propagation de potentiels d'action. Des canaux défectueux conduisent à des maladies graves, notamment l'épilepsie, des arythmies et des syndromes douloureux, ce qui en fait une cible potentielle intéressante pour le développement de médicaments. Pour améliorer notre compréhension de ces assemblages biologiques et éventuellement trouver des traitements spécifiques pour les canalopathies, il est crucial d'étudier la structure et la fonction des canaux ioniques. L'objectif principal de cette thèse a été d'étudier ce type de détails structurels et fonctionnels pour trois canaux ioniques associés aux domaines des capteurs de douleur et des canaux potassiques voltage-dépendants en utilisant des techniques de fluorescence et d'électrophysiologie. Dans le premier projet, nous avons étudié la stœchiométrie des canaux hétéromères Kv2.1 / 6.4 (chapitre trois). La technique du décompte de sous-unités isolées (single subunit counting :ssc) permet de compter les sous-unités marquées par fluorescence d’un complexe isolé en déterminant le nombre d'événements de photoblanchiment, qui apparaissent en sauts irréversibles vers le bas sur les traces de fluorescence. Pour désigner la stœchiométrie la plus probable, nous avons utilisé des calculs de probabilités pondérées et avons constaté que les canaux Kv2.1 / 6.4 s'expriment dans un arrangement 2 : 2. Plus précisément, les études fonctionnelles des canaux concatémériques montrent que les sous-unités Kv6.4 et 2.1 doivent être disposées de manière alternée. Le deuxième projet était également basé sur des expériences de SSC et visait à déterminer l'état oligomérique du nouveau canal ionique TACAN (chapitre quatre). Nous avons trouvé une portion significative de canaux intracellulaires, ce qui a provoqué une fluorescence de fond dans les expériences de SSC traditionnelles réalisées avec les cellules mammifères. Pour améliorer le rapport du signal sur bruit de fond, nous avons effectué des expériences de SSC sur des canaux purifiés qui ont été immobilisés sur des lamelles de verre fonctionnalisées Ni-NTA. En utilisant la méthode de calcul décrite dans le premier projet, nous avons trouvé différents états oligomériques et proposons que les canaux TACAN natifs s'assemblent en tétramères qui sont instables lorsqu'ils sont solubilisés dans un détergent. Dans le dernier projet, nous avons étudié la relation structure-fonction de la sous-unité auxiliaire DPP6 pour les canaux Kv4.2 (chapitre cinq). Ici, nous avons progressivement tronqué le grand domaine extracellulaire de 700 acides aminés de DPP6 et étudié son effet sur les courants macroscopiques en utilisant la technique du cut-open voltage clamp. Nous avons constaté que les sous-unités DPP6 avec un domaine extracellulaire court ne parviennent pas à moduler les propriétés du canal aussi efficacement que la DPP6 pleine longueur. Plus précisément, la seconde moitié du domaine extracellulaire b-propeller de DPP6 est responsable d'une inactivation du canal considérablement accélérée. Sur la base de la structure cristalline du domaine extracellulaire, nous avons proposé qu'un domaine b-propeller stable et possiblement la formation de dimères DPP6 sont responsables de la déstabilisation efficace de l'état du canal ouvert. / Ion channels are key macromolecular complexes expressed in all cell types and are involved in various physiological processes including the generation and propagation of action potentials. Defective channels lead to severe diseases including epilepsy, arrhythmias and pain syndromes making them an interesting potential drug target. To improve our understanding of these biological assemblies and eventually find specific treatments for channelopathies, it is crucial to study the structure and function of ion channels. The main purpose of this thesis has been to investigate such structural and functional details of three ion channel complexes from the field of pain sensors and voltage-gated potassium channels using fluorescence and electrophysiological techniques. In the first project, we studied the stoichiometry of heteromeric Kv2.1/6.4 channel complexes (chapter three). Single subunit counting (SSC) allows to directly count the number of fluorescently labeled subunits by determining the number of irreversible, step-wise photobleaching events. To determine the most probable stoichiometry, we used weighted likelihood calculations and found that Kv2.1/6.4 channels express in a 2:2 arrangement. More precisely, functional studies of concatemeric channels (performed by our collaborators) illustrate that Kv6.4 and 2.1 subunits need to be arranged in an alternating fashion. The second project was also based on SSC experiments and aimed at determining the oligomeric state of the novel ion channel TACAN (chapter four). We found a significant amount of channels in the intracellular which caused background fluorescence in traditional SSC experiments performed in cells. To improve the signal to background ratio, we performed SSC experiments on purified channels that were immobilized on Ni-NTA functionalized glass coverslips. Using the model selection method described in the first project, we found different oligomeric states and propose that native TACAN channels assemble as tetramers which are unstable when solubilized in detergent. In the last project, we investigated the structure-function relation of the auxiliary DPP6 subunit in Kv4.2 channel complexes (chapter five). Here, we progressively truncated DPP6’s 700 amino acids long extracellular domain and studied its effect on macroscopic currents using the cut-open voltage clamp technique. We found that DPP6 subunits with a short extracellular domain fail to modulate the channel properties as efficiently as the full length DPP6. More precisely, the second half of the extracellular b-propeller domain of DPP6 is responsible for drastically accelerated channel inactivation. Based on the crystal structure of the extracellular domain, we proposed that a stable b-propeller domain and possibly DPP6 dimer formation is responsible for destabilizing the open channel state efficiently.
523

Analysis of Amur honeysuckle Stem Density as a Function of Spatial Clustering, Horizontal Distance from Streams, Trails, and Elevation in Riparian Forests, Greene County, Ohio

Grierson, Greg Michael, Jr. 28 May 2021 (has links)
No description available.
524

Počítání vozidel v statickém obraze / Counting Vehicles in Static Images

Zemánek, Ondřej January 2020 (has links)
Tato práce se zaměřuje na problém počítání vozidel v statickém obraze bez znalosti geometrických vlastností scény. V rámci řešení bylo implementováno a natrénováno 5 architektur konvolučních neuronových sítí. Také byl pořízen rozsáhlý dataset s 19 310 snímky pořízených z 12pohledů a zachycujících 7 různých scén. Použité konvoluční sítě mapují vstupní vzorek na mapu hustoty vozidel, ze které lze získat jejich počet a lokalizaci v kontextu vstupního snímku. Hlavním přínosem této práce je porovnání a aplikace dosavadních nejlepších řešení pro počítání objektů v obraze. Většina z těchto architektur byla navržena pro počítání lidí v obraze, proto musely být uzpůsobeny pro potřeby počítání vozidel v statickém obraze. Natrénované modely jsou vyhodnoceny GAME metrikou na TRANCOS datasetu a na velkém spojeném datasetu. Dosažené výsledky všech modelů jsou následně popsány a porovnány.
525

Obslužný program pro colony-picking robot / Control Program for Colony-picking Robot

Matějka, Lukáš January 2012 (has links)
From an overview of most commonly used kinematic conceptions of robotic manipulators, the conception of Cartesian robot was identified as the most suitable for the given task of colony picking. A control system consisting of two modular parts has been designed for the colony picking robot. ColonyCounter module is a set of image processing libraries for identification of microbial colonies in image data and precise localization of individual colonies. This has been achieved by combination of multiple methods, most importantly connected components labelling and Hough circular transform. The second module – ColonyPicker – utilizes output of ColonyCounter module to plan the picking and placing of colonies. Subsequently it controls the transfer process itself using an innovative task planning and executing system.
526

Metody pro obrazovou analýzu populace fotosyntetických buněčných kultur / Photosynthetic cell suspension cultures quantitative image data processing

Vlachynská, Alžběta January 2015 (has links)
This work was carried out in collaboration with the Department of Adaptive Biotechnologies, Global Change Research Centre AS CR. It deals with the quantitative analysis of photosynthetic cell cultures. It uses images captured by a confocal fluorescent microscope to the automatic determining the number of cells in the sample. The work consists of a theoretical analysis, which briefly describes fluorescence and confocal microscopy. It also concisely introduces a microscope Leica TCS SP8 X, which I used to scan data. One capture is devoted to the theory of digital image processing. The second part deskribes the development of algorithm for processing 3D data and simplified algorithm for processing 2D data and its program implementations in a programming environment MATLAB R2013b. Grafical user interface is explained in detail. Done measurement are presented at the conclusion. It mentions compiled sample preparation protocol. The results of the program are compared with manual counting. Number of cells per 1 ml are determined by created program in samples of cell cultures Chenopodium rubrum (Cr) and Solanum lycopersicum (To).
527

Získávání frekventovaných vzorů z proudu dat / Frequent Pattern Discovery in a Data Stream

Dvořák, Michal January 2012 (has links)
Frequent-pattern mining from databases has been widely studied and frequently observed. Unfortunately, these algorithms are not suitable for data stream processing. In frequent-pattern mining from data streams, it is important to manage sets of items and also their history. There are several reasons for this; it is not just the history of frequent items, but also the history of potentially frequent sets that can become frequent later. This requires more memory and computational power. This thesis describes two algorithms: Lossy Counting and FP-stream. An effective implementation of these algorithms in C# is an integral part of this thesis. In addition, the two algorithms have been compared.
528

Garbage collector objektů jazyka PNtalk / Garbage Collector for PNtalk Objects

Mišák, Ján January 2016 (has links)
This thesis deals with the designing of a garbage collector for the PNtalk virtual machine. It describes and rates the approaches and algorithms for an automatic memory management. Four algorithm families ale presented: mark-sweep, mark-compact, copying algorithms and reference counting. At first it describes sequential forms, that pauses running of the main program (mutator), then it describes parallel and concurent forms, that do not pauses the mutator. The thesis also presents generational model of garbage collecting. The following sections briefly introduces object orientated Petri nets. The result of this thesis is the design of the generational garbage collector for the PNtalk virtual machine.
529

Étude Monte Carlo de l’impact de la tomodensitométrie multiénergie sur la précision du calcul de dose en protonthérapie

Lalonde, Arthur 02 1900 (has links)
No description available.
530

Srovnání nástrojů pro mapování bezdomovectví na místní a regionální úrovni / Comparison of Tools for Measuring Homelessness at Local and Regional Level

Růžička, Jiří January 2015 (has links)
The thesis deals with the issue of enumerating and mapping the needs of the homeless. It compares tools for measuring homelessness which are described in literature and shows the way for implementation of measuring within the area of smaller municipalities. Findings about homelessness, homeless phenomenon and services for the homeless published in the literature are discussed at the beginning of the theoretical part. The core fragment of the theoretical part is devoted to a discussion on the basis and ways of measuring homelessness both in the Czech Republic and abroad. Different tools for measuring homelessness are compared in the thesis, appended with commentaries reflecting author's own multiyear experiences with providing services for target group and his involvement in surveys. The empirical part describes the process of verifying the applicability of the given methodology for enumerating and mapping the needs of homeless in practice. The procedures how author reached the final adjustments of the given methodology are described in this part. The modified methodology for counting and mapping the needs of homeless is presented in the conclusion. At final stage the modified methodology is compared with the methodology used for enumerating homeless in the United States.

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