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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.
151

An exploration of cultural identity in creative practice

Domeij, Tina January 2020 (has links)
My work is about the feeling of standing in between two worlds of my cultural heritage. To feel connected but at the same time not connected to them. The feeling of missing out in one of my cultural heritage because of the language that I do not fully speak. I use a traditional craft from that side to build a bridge to fill the gap. It is about combining my heritages and the connection/disconnection and fuse them together into one as I am a person of two cultures. By not putting myself in a box that the society wants me to fit in to, I challenge that norm also in my work. I transformed the traditional craft placed in a room of a house to become jewelry. The wearer is allowed to choose what kind of jewelery it is and it can be placed on many different ways. My work is about investigate the meeting of craft on a body, and body in a craft. Its about to invite the Thai practice to my Swedish practice and vice versa and fuse them together.
152

Multidimensional Highway Construction Cost Indexes Using Dynamic Item Basket

Shrestha, Joseph, Jeong, H. David, Gransberg, Douglas D. 01 August 2017 (has links)
A highway construction cost index (HCCI) is an indicator of the purchasing power of a highway agency. Thus, it must reflect the actual construction market conditions. However, current methods used by most state departments of transportation are not robust enough to meet this primary goal due to (1) a significantly insufficient sample size of bid items used in HCCI calculation; and (2) inability to address the need to track highway construction market conditions in specific submarket segments such as, but not limited to, various project types, sizes, and locations. This study proposes an advanced methodology to overcome these apparent limitations using two new concepts: (1) dynamic item basket; and (2) multidimensional HCCIs. The dynamic item basket process identifies and utilizes an optimum amount of bid-item data to calculate HCCIs in order to minimize the potential error due to a small sample size, which leads to a better reflection of the current market conditions. Multidimensional HCCIs dissect the state highway construction market into distinctively smaller sectors of interest and thus, allow state Departments of Transportation to understand the market conditions with much higher granularity. A framework is developed to integrate these two concepts and a standalone prototype system, named the Dyna-Mu-HCCI System, is developed to automate the data-processing part of the framework. The historical bid data of the Montana Department of Transportation are used to evaluate the performance of the Dyna-Mu-HCCI System and measure the effects of the dynamic item basket (DIB) and multidimensional HCCIs. The results show an eightfold increase in terms of the number of bid items used in calculating HCCIs and at least a 20% increase in terms of the total cost of bid items used. In addition, the multidimensional HCCIs reveal different cost-change patterns from different highway sectors. For example, the bridge construction market historically shows a very different trend compared with the overall highway construction market. The new methodology is expected to aid state Departments of Transportation in making more-reliable decisions in preparing business plans and budgets with more accurate and detailed information about the construction market conditions. Further, the prototype Dyna-Mu-HCCI System is expected to significantly facilitate the HCCI calculation process and rapidly implement this new system.
153

Tillamook Indian basketry : continuity and change as seen in the Adams Collection

Crawford, Ailsa Elizabeth 01 January 1983 (has links)
In the Adams Collection at the Tillamook County Pioneer Museum, Tillamook, Oregon, there are 29 baskets that were probably made between 1880 and 1940. They are mostly of raffia, are somewhat faded from their original, bright, commercial colors, and are generally quite small. Despite the fact that these baskets are well-documented and were made by Tillamook women, they are the sort that have been overlooked by anthropologists and by collectors because of their non-"traditional" appearance. In order to determine what relationship these baskets have to Tillamook basketry made earlier, I analyzed them and 39 Tillamook baskets from four other museum collections for features of structural and.decorative techniques, shape, size, and stitch qualities, and noted the.materials used.
154

Deciphering mRNP – nuclear pore interactions : study of basket protein dynamics in budding yeast

Bensidoun, Pierre 07 1900 (has links)
The export of mRNAs from the nucleus to the cytoplasm is one of many steps along the gene expression pathway and is fundamental for mRNAs to meet with ribosomes for translation in the cytoplasm. Exchanges between nucleus and cytoplasm occur through the nuclear pore complex (NPC), which is a large multi-protein complex embedded in the nuclear membrane and assembled by 30 different proteins the nucleoporins. The nucleoplasmic side of the pore is believed to orchestrate many fundamental nuclear processes. Indeed, a growing body of evidence suggests that the nuclear pore is involved in a broad range of activities including modulation of DNA topology, DNA repair, epigenetic regulation of gene expression, and selective access to exporting molecules. The structural component required for orchestrating those nucleoplasmic functions is the basket, a ∼60- to 80-nm-long structure protruding into the nucleoplasm. The consensus view depicts the basket as a structure assembled by filamentous proteins, TPR (Translocated Promoter Region protein) in humans and by its two paralogues Mlp1 and Mlp2 (myosin-like proteins) in yeast, converging into a distal ring. In the first part of this thesis, we characterized the motion of specific mRNAs at the vicinity of the nuclear periphery. We observed that transcripts scan along the nuclear envelope, likely to find a nuclear pore to be exported. We also showed the scanning behavior was affected upon Mlp1 deletion or truncation as well as upon mutation of the nuclear poly(A) binding protein Nab2. These observations indicated that Mlp1 and hence baskets, as well as specific RNA binding proteins, facilitate the interaction of mRNA with the nuclear periphery. While the canonical structure of the NPC is well established, our understanding of the conditions and factors contributing to the assembly of a basket, as well as the stoichiometry of its components, remains incomplete. Although basket proteins have been implicated in the regulation of gene expression through gene anchoring to the nuclear periphery and in mRNA scanning before export, how this is mediated by Mlp1/2 is poorly understood. Moreover, the dynamics of basket proteins in yeast seem to obey different rules than those of other nucleoporins as their turnover at the pore is faster than any other NPC components. Furthermore, it has been observed that during heat shock Mlp1 and Mlp2 dissociate from nuclear pores and form intra-nuclear granules, sequestering mRNAs and RNA export factors. Yet the mechanism for the formation of these granules or their role during heat shock is poorly understood. In yeast, the nuclear baskets are not associated with all NPCs, as no baskets assemble on the pores adjacent to the nucleolus. Yet, how cells establish these basket-less pores and whether they represent specialized nuclear pores with different functions from basket-containing pores is still unknown. To understand the dynamics of basket assembly and the biological relevance of establishing distinct sets of pores, we dissected the biological processes leading to the formation of baskets. In addition, to highlight potential functional differences between the two types of pores, we identified the interactors of nuclear basket-containing and nucleolar basket-less pores. We showed that assembling a basket is not a default mode for a pore in the nucleoplasm and that active mRNA processing is required to maintain baskets integrity. While mRNA can be found associated with both types of pores, our results suggest that export kinetics may be different on basket-containing and basket-less pores. The eukaryotes organize their nucleus in discrete functional regions and the nuclear envelope has been envisioned as an organelle by and of itself. Our analyzes indicate that mRNAs and Mlp1 participate in an additional degree of nuclear compartmentalization by enabling the formation of a dynamic structure: the basket. Overall my project sheds new light on the nuclear organization and highlights the surprising entanglement between mRNA export and NPC plasticity. / L'exportation des ARN messagers du noyau vers le cytoplasme est l'une des nombreuses étapes de la voie d'expression des gènes et est fondamentale pour que les ARNm rencontrent les ribosomes pour être traduits dans le cytoplasme. Les échanges entre le noyau et le cytoplasme se font par l'intermédiaire du complexe du pore nucléaire, qui est un grand complexe multiprotéique enchâssé dans la membrane nucléaire et assemblé par 30 protéines différentes, les nucléoporines. Le versant nucléoplasmique du pore orchestre de nombreux processus nucléaires fondamentaux. En effet, un nombre croissant d’études suggère que le pore nucléaire est impliqué dans un large éventail d'activités, notamment la modulation de la topologie de l'ADN, la réparation de l'ADN, la régulation épigénétique de l'expression des gènes et l'accès sélectif aux molécules candidates à l’export. Le composant structurel nécessaire pour orchestrer ces fonctions nucléoplasmiques est appelé le panier une structure de ∼60 à 80 nm de long faisant saillie dans le nucléoplasme. Une vision consensuelle dépeint le panier comme une structure assemblée par des protéines filamenteuses convergeant en un anneau distal, TPR (Translocated Promoter Region protein) chez l'homme et par ses deux paralogues Mlp1 et Mlp2 (myosin-like proteins) chez la levure. Dans la première partie de cette thèse, nous avons caractérisé le mouvement d'ARNm spécifiques au voisinage de la périphérie nucléaire. Nous avons observé que les transcrits scannent l'enveloppe nucléaire, probablement pour trouver un pore nucléaire afin d'être exportés. Nous avons également montré que ce comportement était affecté par la délétion ou la troncation de Mlp1 ainsi que par la mutation de la protéine de liaison aux queues poly(A) Nab2. Ces observations indiquent que Mlp1 et donc les paniers, ainsi que des protéines liant l’ARN, facilitent l'interaction des ARNm avec la périphérie nucléaire. Alors que la structure canonique du pore nucléaire est bien établie, notre compréhension des conditions et des facteurs contribuant à l'assemblage du panier, ainsi que de la stoechiométrie de ses composants, reste incomplète. Bien que les protéines du panier soient impliquées dans la régulation de l'expression des gènes par l'ancrage des gènes à la périphérie nucléaire et dans le recrutement des ARNm avant leur export, la manière dont le panier intervient dans ce processus est mal comprise. De plus, la dynamique des protéines du panier chez la levure semble obéir à des 6 règles différentes de celles des autres nucléoporines, car leur renouvellement (turn over) au niveau du pore est plus rapide que celui des autres composants du NPC. De plus, il a été observé que lors d'un choc thermique, Mlp1 et Mlp2 se dissocient des pores nucléaires et forment des granules intra-nucléaires, séquestrant les ARNm et les facteurs d'exportation d'ARN. Pourtant, le mécanisme de formation de ces granules ou leur rôle pendant le choc thermique est mal compris. Chez la levure, le panier nucléaire n'est pas associé à tous les pores nucléaires, et les paniers sont absents des pores adjacents au nucléole. La manière dont les cellules établissent ces pores sans paniers et s'ils représentent des pores nucléaires spécialisés ayant des fonctions différentes des pores contenant des corbeilles n’est pas connue. Pour comprendre la dynamique de l'assemblage des paniers et la pertinence biologique de former de deux types de pores distincts, nous avons disséqué les processus biologiques menant à la formation des paniers. De plus, afin de mettre en évidence les différences fonctionnelles potentielles entre les deux types de pores nous avons étudié les protéines associées aux pores contenant un panier nucléaire et des pores sans panier. Nous avons montré que l'assemblage d'un panier n'est pas un mode par défaut pour un pore dans le nucléoplasme et que la formation et la maturation des ARNm est nécessaire pour maintenir l'intégrité des paniers. Alors que l'ARNm peut être trouvé associé aux deux types de pores, nos résultats suggèrent que la cinétique d’export peut être différente sur les pores avec et sans panier. Les eucaryotes organisent leur noyau en régions fonctionnelles discrètes et l'enveloppe nucléaire a été envisagée comme pouvant être une organelle à part entière. Nos analyses indiquent que les ARNm et Mlp1 participent à un degré supplémentaire de compartimentation nucléaire en permettant la formation d'une structure dynamique : le panier. Mon projet apporte un nouvel éclairage sur l'organisation des compartiments nucléaire et met en évidence l'intrication surprenante entre l'export des ARNm et la plasticité des pores nucléaires.
155

Hierarchical Adaptive Quadrature and Quasi-Monte Carlo for Efficient Fourier Pricing of Multi-Asset Options

Samet, Michael 11 July 2023 (has links)
Efficiently pricing multi-asset options is a challenging problem in computational finance. Although classical Fourier methods are extremely fast in pricing single asset options, maintaining the tractability of Fourier techniques for multi-asset option pricing is still an area of active research. Fourier methods rely on explicit knowledge of the characteristic function of the suitably stochastic price process, allowing for calculation of the option price by evaluation of multidimensional integral in the Fourier domain. The high smoothness of the integrand in the Fourier space motivates the exploration of deterministic quadrature methods that are highly efficient under certain regularity assumptions, such as, adaptive sparse grids quadrature (ASGQ), and Randomized Quasi-Monte Carlo (RQMC). However, when designing a numerical quadrature method for most of the existing Fourier pricing approaches, two key factors affecting the complexity should be carefully controlled, (i) the choice of the vector of damping parameters that ensure the Fourier-integrability and control the regularity class of the integrand, (ii) the high-dimensionality of the integration problem. To address these challenges, in the first part of this thesis we propose a rule for choosing the damping parameters, resulting in smoother integrands. Moreover, we explore the effect of sparsification and dimension-adaptivity in alleviating the curse of dimensionality. Despite the efficiency of ASGQ, the error estimates are very hard to compute. In cases where error quantification is of high priority, in the second part of this thesis, we design an RQMC-based method for the (inverse) Fourier integral computation. RQMC integration is known to be highly efficient for high-dimensional integration problems of sufficiently regular integrands, and it further allows for computation of probabilistic estimates. Nonetheless, using RQMC requires an appropriate domain transformation of the unbounded integration domain to the hypercube, which may originate in a transformed integrand with singularities at the boundaries, and consequently deteriorate the rate of convergence. To preserve the nice properties of the transformed integrand,we propose a model-dependent domain transformation to avoid these corner singularities and retain the optimal efficiency of RQMC. The effectiveness of the proposed optimal damping rule, the designed domain transformation procedure, and their combination with ASGQ and RQMC are demonstrated via several numerical experiments and computational comparisons to the MC approach and the COS method.
156

Microcircuit structures of inhibitory connectivity in the rat parahippocampal gyrus

Barreda Tomás, Federico José 16 May 2023 (has links)
Komplexe Berechnungen im Gehirn werden durch das Zusammenspiel von exzitatorischen und hemmenden Neuronen in lokalen Netzwerken ermöglicht. In kortikalen Netzwerken, wird davon ausgegangen, dass hemmende Neurone, besonders Parvalbumin positive Korbzellen, ein „blanket of inhibition” generieren. Dieser Sichtpunkt wurde vor kurzem durch Befunde strukturierter Inhibition infrage gestellt, jedoch ist die Organisation solcher Konnektivität noch unklar. In dieser Dissertation, präsentiere ich die Ergebnisse unserer Studie Parvabumin positiver Korbzellen, in Schichten II / III des entorhinalen Kortexes und Präsubiculums der Ratte. Im entorhinalen Kortex haben wir dorsale und ventrale Korbzellen beschrieben und festgestellt, dass diese morphologisch und physiologisch ähnlich, jedoch in ihrer Konnektivität zu Prinzipalzellen dorsal stärker als ventral verbunden sind. Dieser Unterschied korreliert mit Veränderungen der Gitterzellenphysiologie. Ähnlich zeige ich im Präsubiculum, dass inhibitorische Konnektivität eine essenzielle Rolle im lokalen Netzwerk spielt. Hemmung im Präsubiculum ist deutlich spärlicher ist als im entorhinalen Kortex, was ein unterschiedliches Prinzip der Netzwerkorganisation suggeriert. Um diesen Unterschied zu studieren, haben wir Morphologie und Netzwerkeigenschaften Präsubiculärer Korbzellen analysiert. Prinzipalzellen werden über ein vorherrschendes reziprokes Motif gehemmt die durch die polarisierte Struktur der Korbzellaxone ermöglicht wird. Unsere Netzwerksimulationen zeigen, dass eine polarisierte Inhibition Kopfrichtungs-Tuning verbessert. Insgesamt zeigen diese Ergebnisse, dass inhibitorische Konnektivität, funktioneller Anforderungen der lokalen Netzwerke zur Folge, unterschiedlich strukturiert sein kann. Letztlich stelle ich die Hypothese auf, dass für lokale inhibitorische Konnektivität eine Abweichung von „blanket of inhibition― zur „maßgeschneiderten― Inhibition zur Lösung spezifischer computationeller Probleme vorteilhaft sein kann. / Local microcircuits in the brain mediate complex computations through the interplay of excitatory and inhibitory neurons. It is generally assumed that fast-spiking parvalbumin basket cells, mediate a non-selective -blanket of inhibition-. This view has been recently challenged by reports structured inhibitory connectivity, but it’s precise organization and relevance remain unresolved. In this thesis, I present the results of our studies examining the properties of fast-spiking parvalbumin basket cells in the superficial medial entorhinal cortex and presubiculum of the rat. Characterizing these interneurons in the dorsal and ventral medial entorhinal cortex, we found basket cells of the two subregions are more likely to be connected to principal cells in the dorsal compared to the ventral region. This difference is correlated with changes in grid physiology. Our findings further indicated that inhibitory connectivity is essential for local computation in the presubiculum. Interestingly though, we found that in this region, local inhibition is lower than in the medial entorhinal cortex, suggesting a different microcircuit organizational principle. To study this difference, we analyzed the properties of fast-spiking basket cells in the presubiculum and found a characteristic spatially organized connectivity principle, facilitated by the polarized axons of the presubicular fast-spiking basket cells. Our network simulations showed that such polarized inhibition can improve head direction tuning of principal cells. Overall, our results show that inhibitory connectivity is differently organized in the medial entorhinal cortex and the presubiculum, likely due to functional requirements of the local microcircuit. As a conclusion to the studies presented in this thesis, I hypothesize that a deviation from the blanket of inhibition, towards a region-specific, tailored inhibition can provide solutions to distinct computational problems.
157

We cannot see what we are not looking for: mapping and conceptualizing linkages between multidimensional inequality and ecosystem services

Elfvengren, Emelie January 2022 (has links)
The global threats of widespread biodiversity loss and climate change impact ecosystems daily, leading to far-reaching consequences for people who benefit from these systems in various ways. Despite these challenges, little is known about the differences in how people derive benefits from nature and who will become increasingly vulnerable to future global environmental change. Previous research has assessed the impact of inequality on nature’s benefits (or ecosystem services), but these efforts have primarily relied on socio-economic inequality measures. These measures overlook potential heterogeneity within groups based on characteristics such as gender, class, and ethnicity. Therefore, a multidimensional approach to understanding inequality is needed. This systematic mapping review aims to map the literature that explores multidimensional inequality in relation to ecosystem services (ES), specifically in terms of three types of ecosystem benefits: experience, use, and money. Key findings were that political-and economic inequalities are most frequently linked to all three types of benefits, with links between political inequality and the use of ES being particularly common in the literature. In contrast, studies that analyze inequalities based on religion, disabilities, and race in relation to ES are least common. Finally, experience is the least explored benefit in relation to inequality, potentially due to the challenges of assessing intangible benefits. This review also highlights the complexities of inequalities acting at different scales and potential trade-offs between inequality categories and ecosystem benefit types. Future research recommendations include further widening the inequality lens (primarily in the cultural and social dimensions) to improve our understanding of who benefits from nature to develop more effective, sustainable, and equitable policies and mitigate future threats.
158

Combinatorial and price efficient optimization of the underlying assets in basket options / Kombinatorisk och priseffektiv optimering av antalet underliggande tillgångar i aktiekorgar

Alexis, Sara January 2017 (has links)
The purpose of this thesis is to develop an optimization model that chooses the optimal and price efficient combination of underlying assets for a equally weighted basket option. To obtain a price efficient combination of underlying assets a function that calculates the basket option price is needed, for further use in an optimization model. The closed-form basket option pricing is a great challenge, due to the lack of a distribution describing the augmented stochastic price process. Many types of approaches to price an basket option has been made. In this thesis, an analytical approximation of the basket option price has been used, where the analytical approximation aims to develop a method to describe the augmented price process. The approximation is done by moment matching, i.e. matching the first two moments of the real distribution of the basket option with an lognormal distribution. The obtained price function is adjusted and used as the objective function in the optimization model. Furthermore, since the goal is to obtain en equally weighted basket option, the appropriate class of optimization models to use are binary optimization problems. This kind of optimization model is in general hard to solve - especially for increasing dimensions. Three different continuous relaxations of the binary problem has been applied in order to obtain continuous problems, that are easier to solve. The results shows that the purpose of this thesis is fulfilled when formulating and solving the optimization problem - both as an binary and continuous nonlinear optimization model. Moreover, the results from a Monte Carlo simulation for correlated stochastic processes shows that the moment matching technique with a lognormal distribution is a good approximation for pricing a basket option. / Syftet med detta examensarbete är att utveckla ett optimeringsverktyg som väljer den optimala och priseffektiva kombinationen av underliggande tillgångar för en likaviktad aktiekorg. För att kunna hitta en priseffektiv kombination av underliggande tillgångar behöver man finna en passande funktion som bestämmer priset på en likaviktad aktiekorg. Prissättningen av dessa typer av optioner är en stor utmaning. Detta är på grund av bristen av en sannolikhetsfördelning som kan beskriva den utökade och korrelerade stokastiska prisprocess som uppstår för en aktiekorg. Många typer av prissättningar har undersökts och tillämpats. I detta arbete har en analytisk approximation använts för att kunna beskriva den underliggande pris processen approximativt. Uppskattningen görs genom att matcha de tvåförsta momenten av den verkliga fördelningen med motsvarande moment för en lognormal fördelning. Den erhållna prisfunktionen justeras och används som målfunktionen i optimeringsmodellen. Binära ickelinjära optimeringsproblem är i allmänhet svåra att lösa - särskilt för ökande dimensioner av variabler. Tre olika kontinuerliga omformuleringar av det binära optimeringsproblemet har gjorts för att erhålla kontinuerliga problem som är lättare att lösa. Resultaten visar att en optimal och priseffektiv kombination av underliggande aktier är möjlig att hitta genom att formulera ett optimeringsproblem - både som en binär och kontinuerlig ickelinjär optimeringsmodell. Dessutom visar resultaten från en Monte Carlo-simulering, i detta fall för korrelerade stokastiska processer, att moment matching metoden utförd med en lognormal fördelning är en god approximation för prissättningen av aktiekorgar.
159

Mapping of the electrical activity of human atria. Multiscale modelling and simulations

Martínez Mateu, Laura 25 June 2018 (has links)
La fibrilación auricular es una de las arritmias cardíacas más comunes observadas en la práctica clínica. Por lo tanto, es de vital importancia desarrollar nuevas tecnologías destinadas a diagnosticar y acabar con este tipo de arritmia, para mejorar la calidad de vida de los pacientes y reducir los costes de los sistemas nacionales de salud. En los últimos años ha aumentado el uso de las nuevas técnicas de mapeo auricular, basadas en sistemas multi-electrodo para mapear la actividad eléctrica en humanos. Dichas técnicas permiten localizar y ablacionar los impulsores de la fibrilación auricular, como son las fuentes focales o los rotores. Sin embargo, todavía existe incertidumbre sobre su precisión y los procedimientos experimentales para su análisis están limitados debido a su carácter invasivo. Por lo tanto, las simulaciones computacionales son una herramienta muy útil para superar estas limitaciones, al permitir reproducir con fidelidad las observaciones experimentales, dividir el problema bajo estudio en sub-estudios más simples, y realizar investigaciones preliminares imposibles de llevar a cabo en el práctica clínica. Esta tesis doctoral se centra en el análisis de la precisión de los sistemas de mapeo multi-electrodo a través de modelos y simulaciones computacionales. Para ello, desarrollamos modelos realistas multi-escala con el objetivo de simular actividad eléctrica auricular reentrante, en primer lugar en una lámina de tejido auricular, y en segundo lugar en las aurículas completas. Posteriormente, analizamos los efectos de las configuraciones geométricas multi-electrodo en la precisión de la localización de los rotores, mediante el uso de agrupaciones multi-electrodo con distancias inter-electrodo equidistantes, así como a través de catéteres de tipo basket con distancias inter-electrodo no equidistantes. Después de calcular los electrogramas unipolares intracavitarios, realizamos mapas de fase, detecciones de singularidad de fase para rastrear los rotores, y mapas de frecuencia dominantes. Finalmente, descubrimos que la precisión de los sistemas de mapeo multi-electrodo depende de su posición dentro de la cavidad auricular, de la distancia entre los electrodos y el tejido, de la distancia inter-electrodo, y de la contribución de las fuentes de campo lejano. Además, como consecuencia de estos factores que pueden afectar a la precisión de los sistemas de mapeo multi-electrodo, observamos la aparición de rotores falsos que podrían contribuir al fracaso de los procesos de ablación de la fibrilación auricular. / Atrial fibrillation is one of the most common cardiac arrhythmias seen in clinical practice. Therefore, it is of vital importance to develop new technologies aimed at diagnosing and terminating this kind of arrhythmia, to improve the quality of life of patients and to reduce costs to national health systems. In the last years, new atrial mapping techniques based on multi-electrode systems are increasingly being used to map the atrial electrical activity in humans and localise and target atrial fibrillation drivers in the form of focal sources or rotors. However, significant concerns remain about their accuracy and experimental approaches to analyse them are limited due to their invasive character. Therefore, computer simulations are a helpful tool to overcome these limitations since they can reproduce with fidelity experimental observations, permit to split the problem to treat into more simple substudies, and allow the possibility of performing preliminary investigations impossible to carry out in the clinical practice. This PhD thesis is focused on the analysis for accuracy of the multielectrode mapping systems through computational models and simulations. For this purpose, we developed realistic multiscale models in order to simulate atrial electrical reentrant activity, first in a sheet of atrial tissue and, then, in the whole atria. Then, we analysed the effects of the multi-electrode geometrical configurations on the accuracy of localizing rotors, by using multi-electrode arrays with equidistant inter-electrode distances, as well as multi-electrode basket catheters with non-equidistant inter-electrode distances. After computing the intracavitary unipolar electrograms, we performed phase maps, phase singularity detections to track rotors, and dominant frequency maps. We finally found out that the accuracy of multi-electrode mapping systems depends on their position inside the atrial cavity, the electrode-to-tissue distance, the inter-electrode distance, and the contribution of far field sources. Furthermore, as a consequence of these factors, false rotors might appear and could contribute to failure of atrial fibrillation ablation procedures. / La fibril·lació auricular és una de les arítmies cardíaques més comuns observades en la pràctica clínica. Per tant, és de vital importància desenvolupar noves tecnologies destinades a diagnosticar i acabar amb aquest tipus d'arítmia, per tal de millorar la qualitat de vida dels pacients i reduir els costos dels sistemes nacionals de salut. En els últims anys, ha augmentat l'ús de les noves tècniques de mapeig auricular, basades en sistemes multielèctrode per a mapejar l'activitat elèctrica auricular en humans. Aquestes tècniques permeten localitzar i ablacionar els impulsors de la fibril·lació auricular, com són les fonts focals o els rotors. No obstant això, encara hi ha incertesa sobre la seua precisió i els procediments experimentals per al seu anàlisi estan limitats a causa del seu caràcter invasiu. Per tant, les simulacions computacionals són una eina molt útil per a superar aquestes limitacions, en permetre reproduir amb fidelitat les observacions experimentals, dividir el problema sota estudi en subestudis més simples, i realitzar investigacions preliminars impossibles de dur a terme en el pràctica clínica. Aquesta tesi doctoral es centra en l'anàlisi de la precisió del sistemes de mapeig multielèctrode mitjançant els models i les simulacions computacionals. Per a això, desenvolupàrem models realistes multiescala per tal de simular activitat elèctrica auricular reentrant, en primer lloc en una làmina de teixit auricular, i en segon lloc a les aurícules completes. Posteriorment, analitzàrem els efectes de les configuracions geomètriques multielèctrode en la precisió de la localització dels rotors, mitjançant l'ús d'agrupacions multielèctrode amb distàncies interelèctrode equidistants, així com catèters de tipus basket amb distàncies interelèctrode no equidistants. Després de calcular els electrogrames unipolars intracavitaris, vam realitzar mapes de fase, deteccions de singularitat de fase per a rastrejar els rotors, i mapes de freqüència dominants. Finalment, vam descobrir que la precisió dels sistemes de mapeig multielèctrode depèn de la seua posició dins de la cavitat auricular, de la distància entre els elèctrodes i el teixit, de la distància interelèctrode, i de la contribució de les fonts de camp llunyà. A més, com a conseqüència d'aquests factors, es va observar l'aparició de rotors falsos que podrien contribuir al fracàs de l'ablació de la fibril·lació auricular. / Martínez Mateu, L. (2018). Mapping of the electrical activity of human atria. Multiscale modelling and simulations [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/104604
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Träningsupplägg som leder till framgång inom 3x3 basket : En intervjustudie med landslagsledare i Sverige och ledande världsmästarnationen Serbien

Glavcic, Djordje, Hallström, Felix January 2021 (has links)
Syfte och frågeställningar: Syftet med denna studie var att belysa hur serbiska och svenska landslagstränare planerar en säsong i 3x3 basket. Förhoppningsvis kommer uppfattningen förbättras om vad som kan påverka och vilka delar som är viktiga i träningsuppläggen. Anledningen till att Serbien undersöks är på grund av att de är en världsledande nation inom 3x3 basket och att deras träningsupplägg kan vara en anledning till deras framgång. Studien strävar efter att svara på följande frågeställningar: ●  Vad är orsaken till framgångarna för det serbiska 3x3 landslaget? ●  Vad anser 3x3 landslagstränarna i Serbien och Sverige är viktiga delar i träningsupplägget under en säsong, med fokus på aeroba och anaeroba förmågor? ●  Vilka orsaker upplever tränarna i Serbien och Sverige påverkar träningsupplägget? Metod: Syfte och frågeställningarna besvarades med hjälp av en kvalitativ intervjustudie. Den kvalitativa datainsamlingen har sammanställts och bearbetats genom meningskoncentreringsmodellen i programmet NVivo-version 12. Resultat: Studien påvisar att Serbien och Sverige har två olika tillvägagångsätt när det kommer till planeringen och utförandet av sina träningsupplägg. Analys av data ledde oss till en huvudorsak som visades påverka hur utformningen av ett träningsupplägg för de aeroba och anaeroba förmågorna kan komma att se ut. Huvudorsaken påvisar att träningsupplägget ser annorlunda ut eftersom serbiska herrlandslaget enbart spelar 3x3 basket. Utifrån huvudorsaken förekom också att träningsupplägget utformas beroende på tiden som tränarna har att spendera med laget och antal turneringar som spelas under en säsong. En annan orsak som påverkar träningsupplägget är tränarnas individuella erfarenheter och tillgångar. Slutsats: Studiens slutsats är att det svenska träningsupplägget kan förbättras och att Serbien ständigt försöker utveckla sitt redan framgångsrika träningsupplägg. Det svenska träningsupplägget för utveckling av aeroba och anaeroba förmågor behöver planeras och struktureras för att spelarna ska uppnå bättre form. Slutsatsen är att rekrytering av spelare som enbart ska spela 3x3 basket skulle bidra till bättre resultat för både de serbiska damerna och hela svenska landslaget. Utformandet av sportens kravprofil i Sverige skulle kunna leda till bättre planering av när och hur landslaget bör samlas och börja träna. / <p>Ämneslärarprogrammet, Specialidrott.</p>

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