Tesi sul tema "Connectivity"
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1
Farris, Jennifer. "Connectivity". VCU Scholars Compass, 2009. http://scholarscompass.vcu.edu/etd/1747.
Testo completoAbstract (sommario):
Create a place for learning Develop an interior system that addresses the under utilized spaces in existing higher education schools directed towards distance learning Design a place for one and a place for few, within a place for many Traditional classroom/school environments were developed around a specific program that addresses the needs of a teacher-class environment. Distance learning programs are introducing a new approach to higher education and require a new approach to learning environments. The goal of this project is to understand the development of the traditional classroom environment in order to assess the changes that need to be made in order to design a space that addresses the needs of a new learning environment. The study of the technical challenges, as well as the flow and circulation of distance learning classrooms will create a platform for change. Efficiency and effectiveness are the key ideas in developing this new program. Classrooms that are used for a variety of purposes need to be considered in a new way. By studying the daily functions of these new learning environments we will find ways to re-invent existing spaces that can adapt to the students, their needs, and the financial benefits for the administration that take advantage of the available resources.
2
Lindgren, Amy Jo. "Perceptive Connectivity". Thesis, Montana State University, 2008. http://etd.lib.montana.edu/etd/2008/lindgren/LindgrenA0808.pdf.
Testo completoAbstract (sommario):
This thesis will investigate how architecture can heighten the experience of obtaining information in a sensual environment. As such, I will explore the use of perception as a physical and mental tool to gather and share information of one\'s sensual environment. I have looked at perception into two parts, Activity and Passivity. Activity is defined as obtaining information of an environment through sensory experience focusing on sight, sound and touch. Passivity is the way in which our minds filter and render the physical environment into memorable experiences. By reestablishing a connection to the sensory environment we open ourselves to an opportunity to share our experiences with others. This project will be a unique information center that explores the concept of gathering the sensual information of a particular area and analyzing said information to formulate characteristics of place.
3
Rahal, Line. "Imagerie fonctionnelle ultrasonore du cerveau pour l'étude, le suivi et le traitement de la douleur aiguë et chronique". Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLET041.
Testo completoAbstract (sommario):
Ces travaux de thèse visaient à démontrer l’intérêt de l’imagerie fonctionnelle ultrasonore pour la définition et le suivi de traitements thérapeutiques des manifestations douloureuses aiguës et chroniques. Dans le cadre d’un projet commun mêlant physique des ondes, imagerie, neurosciences et douleur, nous avons montré que cette jeune technologie d’imagerie pouvait être appliquée à l’imagerie de la douleur chez le petit animal anesthésié, à différents niveaux du système nerveux.Dans le but d’avoir une anesthésie adaptée, stable, reproductible d’un animal à l’autre, et contenant le moins d’agents modulateurs de la douleur possible, nous avons comparé six protocoles d’anesthésie différents. Cette étude a conclu que l’utilisation d’un mélange de kétamine et de médétomidine était le meilleur compromis pour nos futures expérimentations en douleur.La première étude sur les processus de la douleur s’est concentrée sur le test à la formaline, un modèle bien caractérisé de douleur inflammatoire court terme (1h). En effet, notre souhait était de débuter sur un modèle de douleur aiguë le plus court possible pouvant être réalisé chez l’animal anesthésié. Sur ce modèle, nous n’avons observé aucun changement significatif de connectivité fonctionnelle dans le cerveau des rats injectés. Nous avons alors choisi de nous tourner vers des modèles de douleur inflammatoire plus persistants.La seconde étude de cette thèse a porté sur l’étude des altérations de connectivité fonctionnelle et d’états cérébraux dans deux modèles de douleur inflammatoire : un modèle à court terme, induit par injection unilatérale d’adjuvant de Freund, et un modèle à long terme, qui est la polyarthrite induite par adjuvant (quatre semaines d’inflammation bilatérale). Tandis que nous n’avons pas obtenu de résultats significatifs d’altérations fonctionnelles dans le modèle court terme, le modèle long terme nous a apporté de nombreuses informations sur les altérations du système nerveux central pendant le processus de chronicisation.Enfin, la dernière étude a porté sur l’imagerie fonctionnelle ultrasonore des ganglions trigéminaux, structures du système nerveux périphérique, à la fois petites et profondes. Nous avons cherché à caractériser la réponse vasculaire de ces ganglions suite à des stimulations nociceptives mécaniques et chimiques de la cornée chez le rat anesthésié. Cette étude nous a permis de confirmer les observations obtenues par immunohistochimie du proto-oncogène c-fos et de valider l’imagerie fonctionnelle ultrasonore comme modalité pour l’imagerie de l’activation des ganglions trigéminaux chez le rat anesthésié, pour l’étude de la douleur trigéminaleThose thesis works aimed at demonstrating the value of functional ultrasound imaging for the definition and the tracking of acute and chronic pain therapeutic treatments. As part of a common project intertwining wave physics, imaging, neurosciences and pain, we demonstrated that this young imaging technology can be applied to pain imaging on the anesthetized small animal, at different levels of the nervous system.With the aim of obtaining an adapted anaesthesia, stable, reproducible from one animal to another, and containing as less pain modulating agents as possible, we compared six different anaesthetics protocols. This study was concluded by the use of the ketamine and medetomidine mixture as the best compromise for our future experiments in pain.The first study on pain processes has focused on the formaline test, a well characterized model of short term inflammatory pain (1h). Indeed, our wish was to start with an acute pain model as short as possible which may be performed on the anesthetized animal. With this model, we didn’t observe any significant change of functional connectivity in the brain of the injected rats. We then chose to turn to more ongoing models of inflammatory pain.The second study of this thesis dealt with the study of the functional connectivity and brain states alterations in two models of inflammatory pain: a short term model, induced by unilateral injection of Freund’s adjuvant, and a long term model, which is adjuvant induced polyarthritis (four weeks of bilateral inflammation). While we didn’t obtain significant results of functional alterations in the short term model, the long term model gave us ample information on the central nervous system alterations during the chronification process.Finally, the last study concerns the ultrasound functional imaging of the trigeminal ganglions, peripheral nervous system structures, both small and deeply located. We tried to characterize the vascular response of those ganglions following mechanical and chemical nociceptive stimulations of the cornea on the anesthetized rat. This study allowed us to confirm the observations obtained by immunohistochemistry of the proto-oncogene c-fos and to validate the functional ultrasound imaging as a modality for the imaging of the trigeminal ganglions in the anesthetized rat, for the study of trigeminal pain
4
Holroyd, A. E. "Percolation beyond connectivity". Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604193.
Testo completoAbstract (sommario):
Percolation models are of interest both for the wide range of their physical applications and for the mathematical challenges which they present. The basic model is as follows. Starting from an infinite connected graph such as the hypercubic lattice, each edge is declared 'open' with probability p or 'closed' otherwise, independently of all others. The standard theory is primarily concerned with the existence (or not) of infinite connected components of the graph of open edges, [2]. Various extensions of the basic model have been studied in detail, [1, 2, 5]. In this work we extend the model in a direction which has received less attention: rather than studying connected components, we consider other graph properties analogous to connectivity. We explore this idea with particular reference to two such properties which have important physical applications, [3, 4]: entanglement and rigidity. Roughly speaking, the meaning of these terms is as follows. A graph in three-dimensional space is entangled if it cannot be 'pulled apart' when the edges are regarded as physical connections made of elastic. A graph is rigid if it cannot be 'deformed' when the edges are regarded as solid rods which can pivot at the vertices. We formalise these intuitive notions for both finite and infinite graphs. In the case of infinite graphs this involves overcoming interesting challenges which are related to the issue of boundary conditions. Having defined entanglement and rigidity formally, we consider entangled and rigid graphs in the percolation model. We prove that (under suitable conditions) there is a genuine phase transition for each, occurring at critical probabilities which differ from the usual critical probability for connectivity percolation. For p below the appropriate critical probability, we explore the size of finite entangled or rigid components. For p greater than the appropriate critical probability we study the question of uniqueness of the infinite entangled or rigid component. We prove several relevant theorems including uniqueness for entanglement for large p, and uniqueness for rigidity for almost all p.
5
Otera, Daniele Ettore. "Asymptotic topology of groups connectivity at infinity and geometric simple connectivity". Paris 11, 2006. http://www.theses.fr/2006PA112050.
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Holtkamp, Andreas [Verfasser]. "Connectivity in graphs and digraphs : maximizing vertex-, edge- and arc-connectivity with an emphasis on local connectivity properties / Andreas Holtkamp". Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2013. http://d-nb.info/1038598796/34.
Testo completo
7
Hawes, Steven Maxwell. "Modelling reef fish connectivity: Investigating the biological mechanisms that influence connectivity patterns". Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/19662.
Testo completoAbstract (sommario):
Biophysical dispersal models (BDMs) — a hydrodynamic model coupled with a biological model — lend themselves to inferring potential connectivity patterns, as experimental studies using current methods are inherently difficult over extended spatial and temporal scales. This thesis explored the biological processes that affect the connectivity patterns of ichthyoplankton using four related data chapters. The first data chapter, a meta-analysis of connectivity studies using BDMs, investigated both trends and consequences of modelling choices on derived connectivity patterns. The results of this meta-analysis provide a useful framework on parameter choice for future consideration of connectivity studies. The second data chapter is an experiment measuring the ontogenetic vertical migration of reef fish off the coast of south-eastern Australia. The ichthyoplankton sampled demonstrated deeper migration with both increasing ontogenetic stage and length. The third data chapter is a theoretical modelling chapter that investigated the effect of different swimming and migration behaviours and differences in the parameterisation and implementation of vertical migration in a BDM. The fourth data chapter synthesised the results from the previous three data chapters and explored the predicted connectivity patterns of an endemic and threatened Australian reef fish, the black cod (Epinephelus daemelii) using a BDM. E. daemelii larvae showed strong connections to both the natal and proximate regions. Within the context of the current marine protected area (MPA) network of NSW, strong settlement regions had only moderate or no no-take areas. The results of this thesis increase our understanding of the influence of behaviour on the dispersal patterns of marine larvae along the east Australian coast.
8
Edde, Manon. "Approche multimodale de connectivité fonctionnelle et structurelle pour l’analyse du déclin cognitif au cours du vieillissement : étude au sein de la cohorte des 3Cités". Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEP011.
Testo completoAbstract (sommario):
Le vieillissement s’accompagne de modifications cérébrales dont l’hétérogénéité expliquerait en partie la variabilité inter-individuelle du déclin cognitif. Ces modifications concernent aussi bien les aspects structurels que fonctionnels. L’imagerie cérébrale multimodale a apporté des éléments de compréhension sur la relation structure-fonction, mais reste peu étudiée dans le cadre du vieillissement. Au cours de ce travail, la connectivité fonctionnelle de repos (CF) et structurelle (CS) prélevées dans l’espace natif ont été explorées chez 120 sujets âgés (cohorte 3C) afin d’étudier leur lien avec les trajectoires cognitives modélisées sur les 12 ans de suivi. Dans notre échantillon, les niveaux de CF inter-hémisphérique élevés sont associés avec les altérations globales du parenchyme cérébral (atrophie de la substance grise et charge lésionnelle de la substance blanche) et avec le déclin en mémoire épisodique. Les paramètres de diffusion corrigés de l’eau libre et extraits du faisceau cingulaire reconstruit par tractographie sont associés au déclin en fluence verbale. D’autre part, une CF élevée et une CS basse entre le cortex cingulaire postérieur ventral (vPCC) et le precuneus A7m sont associés avec le déclin en mémoire épisodique, indépendamment du volume hippocampique. Enfin, les sujets âgés présentent un déficit de réorganisation de l’architecture fonctionnelle de repos à court terme après la réalisation d’une tâche d’apprentissage. Ainsi, le vieillissement cérébral s’accompagne de différents types de modifications de CF (augmentation, diminution, déficit de réorganisation à court terme) offrant ainsi au cerveau un répertoire de réponse plus complexe que la CSAging is associated with changes in the brain, the heterogeneity of which partly explains the inter-individual variability of cognitive decline. These changes concern both the structural and functional aspects. Multimodal brain imaging has provided some insights into the structure-function relationship, but this has been little studied in the context of aging. In this work, functional rest (CF) and structural (CS) connectivity from native space were explored in 120 elderly subjects (cohort 3C) to study their relationship to cognitive trajectories modeled on the 12 years of follow-up. In our sample, elevated interhemispheric CF levels are associated with global changes in cerebral parenchyma (gray matter atrophy and white matter injury burden) and episodic memory decline. The diffusion parameters corrected for free-water, extracted from the cingulum tract are associated with the decline in verbal fluency. On the other hand, high CF and low CS between posterior ventral cingulate cortex (vPCC) and precuneus A7m are associated with episodic memory decline, regardless of hippocampal volume. Finally, the elderly subjects present a deficit of short-term reorganization of the rest-functional architecture after a learning task. Thus, cerebral aging is associated with different patterns of CF changes (increase, decrease, short-term reorganization deficit) thus providing to the brain a more complex response repertoire than CS
9
Garingo, Gary D. "JAVA based data connectivity". Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1997. http://handle.dtic.mil/100.2/ADA342181.
Testo completoAbstract (sommario):
Thesis (M.S. in Software Engineering) Naval Postgraduate School, September 1997."September 1997." Thesis advisor(s): LuQi, V. Berzins. Includes bibliographical references (p. 63). Also available online.
10
Kandimalla, Jyothi Manju Bhargavi, Aditya Vanam e Prathap Mathiyalagan. "Wireless Network Connectivity Measure". Thesis, Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-16655.
Testo completoAbstract (sommario):
The efficiency to which a wireless multi node network is connected is generally measured by the probability that all the nodes are connected to a master node or connected to a master node via other connected node. The grade of connectivity measures how easily and reliably a packet sent by a node can reach another node. Our thesis work is aimed to find connectivity measurement between the nodes in a wireless multi node network. The result is investigated by randomly placing all the nodes in a given area of 38*38 meters and by estimating the connectivity of the whole network. The sub goals of the thesis are To Design a link metric To Find a Routing algorithm which provides information about neighboring nodesAchieving the expected results from this thesis work, it can be a contribution to the research in the measure of connectivity for a wireless multi-node network. By using the available routing algorithm and by setting up appropriate threshold for (i) Good connectivity (ii) Average connectivity (iii) bad connectivity, the status (connectivity measure) is informed to the master node (teacher node) in the network, so that the life time of the whole network is enhanced. Various results and solutions are provided and discussed for the above stated problem from the practical experiments.
11
Gawetski, Krys. "Java data base connectivity". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0013/MQ31577.pdf.
Testo completo
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Al, Karim Tayeb. "An analysis of connectivity /". Online version of thesis, 2007. http://hdl.handle.net/1850/5290.
Testo completo
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French, Leon Hayes. "Bioinformatics for neuroanatomical connectivity". Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/40369.
Testo completoAbstract (sommario):
Neuroscience research is increasingly dependent on bringing together large amounts of data collected at the molecular, anatomical, functional and behavioural levels. This data is disseminated in scientific articles and large online databases. I utilized these large resources to study the wiring diagram of the brain or ‘connectome’. The aims of this thesis were to automatically collect large amounts of connectivity knowledge and to characterize relationships between connectivity and gene expression in the rodent brain. To extract the knowledge embedded in the neuroscience literature I created the first corpus of neuroscience abstracts annotated for brain regions and their connections. These connections describe long distance or macroconnectivity between brain regions. The collection of over 1,300 abstracts allowed accurate training of machine learning classifiers that mark brain region mentions (76% recall at 81% precision) and neuroanatomical connections between regions (50% sentence level recall at 70% precision). By automatically extracting connectivity statements from the Journal of Comparative Neurology I generated a literature based connectome of over 28,000 connections. Evaluations revealed that a large number of brain region descriptions are not found in existing lexicons. To address this challenge I developed novel methods that allow mapping of brain region terms to enclosing structures. To further study the connectome I moved from scientific articles to large online databases. By employing resources for gene expression and connectivity I showed that patterns of gene expression correlate with connectivity. First, two spatially anti-correlated patterns of mouse brain gene expression were identified. These signatures are associated with differences in expression of neuronal and oligodendrocyte markers, suggesting they reflect regional differences in cellular populations. Expression level of these genes is correlated with connectivity degree, with regions expressing the neuron-enriched pattern having more incoming and outgoing connections with other regions. Finally, relationships between profiles of gene expression and connectivity were tested. Specifically, I showed that brain regions with similar expression profiles tend to have similar connectivity profiles. Further, optimized sets of connectivity linked genes are associated with neuronal development, axon guidance and autistic spectrum disorder. This demonstration of text mining and large scale analysis provides new foundations for neuroinformatics.
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Nurafza, Peyman. "Connectivity of overlapping sandbodies". Thesis, Imperial College London, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436372.
Testo completo
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Simmonite, Molly. "Cerebral connectivity in psychosis". Thesis, University of Nottingham, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.606849.
Testo completoAbstract (sommario):
The central pathological process underlying schizophrenia remains unknown. During recent decades evidence from MRI studies investigating the integrity of distributed networks and EEG studies examining the recruitment of diverse brain regions has converged to support impaired coordination of brain regions as the pathological process of schizophrenia. This impaired coordination is often described as a disturbance of cerebral connectivity. However, a number of issues remain unresolved, regarding the heritability, mechanism and specificity of impaired coordination. This work uses both EEG techniques and fMRI to address these questions. In particular, EEG features previously reported in established illness were examined in tmaffected first-degree relatives, with the goal of assessing the extent to which coordination disturbances are present in those with genetic vulnerability for the ilh1ess. The main findings are reduced error related negativity (ERN) amplitudes and attenuated event-related low-frequency oscillations in unaffected siblings of patients with schizophrenia, indicating these abnormalities are not purely an expression of illness. The examination of cross frequency coupling in schizophrenia provides evidence for an abnormal hierarchy of oscillations, including reduced low frequency phase modulation of high frequency amplitude. This supports the hypothesis that the mechanism of impaired recruitment of distributed brain networks in schizophrenia is an attenuation of cross frequency coupling. The reported fMRI investigations demonstrated that, disturbances of the salience network, thought to govern the switch between states of brain connectivity, occur in both schizophrenia and bipolar disorder. The presence of abnormalities in patients with bipolar disorder that are similar in nature, yet less severe in comparison with those found in patients with schizophrenia supports the idea of a continuum of psychotic illness. Additionally relationships are present between functional connectivity measures of brain networks and the dimension of impairment, which is a cardinal feature of Kraepelin's concept of schizophrenia but is also found to a lesser degree in bipolar disorder.
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Brettell, Nicholas John. "Aspects of Matroid Connectivity". Thesis, University of Canterbury. School of Mathematics and Statistics, 2014. http://hdl.handle.net/10092/9215.
Testo completoAbstract (sommario):
Connectivity is a fundamental tool for matroid theorists, which has become increasingly important in the eventual solution of many problems in matroid theory. Loosely speaking, connectivity can be used to help describe a matroid's structure. In this thesis, we prove a series of results that further the knowledge and understanding in the field of matroid connectivity. These results fall into two parts.
First, we focus on 3-connected matroids. A chain theorem is a result that proves the existence of an element, or elements, whose deletion or contraction preserves a predetermined connectivity property. We prove a series of chain theorems for 3-connected matroids where, after fixing a basis B, the elements in B are only eligible for contraction, while the elements not in B are only eligible for deletion. Moreover, we prove a splitter theorem, where a 3-connected minor is also preserved, resolving a conjecture posed by Whittle and Williams in 2013.
Second, we consider k-connected matroids, where k >= 3. A certain tree, known as a k-tree, can be used to describe the structure of a k-connected matroid. We present an algorithm for constructing a k-tree for a k-connected matroid M. Provided that the rank of a subset of E(M) can be found in unit time, the algorithm runs in time polynomial in |E(M)|. This generalises Oxley and Semple's (2013) polynomial-time algorithm for constructing a 3-tree for a 3-connected matroid.
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James, Adam. "Connectivity of Hurwitz spaces". Thesis, University of Birmingham, 2013. http://etheses.bham.ac.uk//id/eprint/4389/.
Testo completoAbstract (sommario):
Let G be a finite group and C = (C1; : : : ;Cr) a collection of conjugacy classes of G. The Hurwitz space H(G;C) is the space of Galois covers of the Riemann Sphere with monodromy group G, and ramification type C. Points of the Hurwitz space can be parameterised combinatorially by Nielsen tuples: tuples of elements of G with product one. There is a correspondence between connected components of H(G;C) and orbits of the braid group on the set of Nielsen tuples. In this thesis we consider the problem of determining the number of components of the Hurwitz space for A\(_5\) and A\(_6\). For both groups we give a complete classification of the braid orbits for all types C. We show that when there exists more than one orbit then Fried's lifting invariant distinguishes these orbits.
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Varga, Romy Carleton University Dissertation Mathematics. "Graph connectivity augmentation problems". Ottawa, 1996.
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Kabbara, Aya. "Estimation des réseaux cérébraux à partir de l’EEG-hr : application sur les maladies neurologiques". Thesis, Rennes 1, 2018. http://www.theses.fr/2018REN1S028/document.
Testo completoAbstract (sommario):
Le cerveau humain est un réseau très complexe. Le fonctionnement cérébral ne résulte donc pas de l'activation de régions cérébrales isolées mais au contraire met en jeu des réseaux distribués dans le cerveau (Bassett and Sporns, 2017; McIntosh, 2000). Par conséquent, l'analyse de la connectivité cérébrale à partir des données de neuroimagerie occupe aujourd'hui une place centrale dans la compréhension des fonctions cognitives (Sporns, 2010). Grâce à son excellente résolution spatiale, l'IRMf est devenue l'une des méthodes non invasives les plus couramment utilisées pour étudier cette connectivité. Cependant, l'IRMf a une faible résolution temporelle ce qui rend très difficile le suivi de la dynamique des réseaux cérébraux. Un défi considérable en neuroscience cognitive est donc l'identification et le suivi des réseaux cérébraux sur des durées courtes (Hutchison et al., 2013), généralement <1s pour une tâche de dénomination d'images, par exemple. Jusqu'à présent, peu d'études ont abordé cette question qui nécessite l'utilisation de techniques ayant une résolution temporelle très élevée (de l'ordre de la ms), ce qui est le cas pour la magnéto- ou l'électro-encéphalographie (MEG ou EEG). Cependant, l'interprétation des mesures de connectivité à partir d'enregistrements effectués au niveau des électrodes (scalp) n'est pas simple, car ces enregistrements ont une faible résolution spatiale et leur précision est altérée par les effets de conduction par le volume (Schoffelen and Gross, 2009). Ainsi, au cours des dernières années, l'analyse de la connectivité fonctionnelle au niveau des sources corticales reconstruites à partir des signaux du scalp a fait l'objet d'un intérêt croissant. L'avantage de cette méthode est d'améliorer la résolution spatiale, tout en conservant l'excellente résolution temporelle de l'EEG ou de la MEG (Hassan et al., 2014; Hassan and Wendling, 2018; Schoffelen and Gross, 2009). Cependant, l'aspect dynamique n'a pas été suffisamment exploité par cette méthode. Le premier objectif de cette thèse est de montrer comment l'approche « EEG connectivité source » permet de suivre la dynamique spatio-temporelle des réseaux cérébraux impliqués soit dans une tache cognitive, soit à l'état de repos. Par ailleurs, les études récentes ont montré que les désordres neurologiques sont le plus souvent associés à des anomalies dans la connectivité cérébrale qui entraînent des altérations dans des réseaux cérébraux «large-échelle» impliquant des régions distantes (Fornito and Bullmore, 2014). C'est particulièrement le cas pour l'épilepsie et les maladies neurodégénératives (Alzheimer, Parkinson) qui constituent, selon l'OMS, un enjeu majeur de santé publique. Dans ce contexte, la demande clinique est très forte pour de nouvelles méthodes capables d'identifier des réseaux pathologiques, méthodes simples à mettre en œuvre et surtout non invasives. Ceci est le deuxième objectif de cette thèseThe human brain is a very complex network. Cerebral function therefore does not imply activation of isolated brain regions but instead involves distributed networks in the brain (Bassett and Sporns, 2017, McIntosh, 2000). Therefore, the analysis of the brain connectivity from neuroimaging data has an important role to understand cognitive functions (Sporns, 2010). Thanks to its excellent spatial resolution, fMRI has become one of the most common non-invasive methods used to study this connectivity. However, fMRI has a low temporal resolution which makes it very difficult to monitor the dynamics of brain networks. A considerable challenge in cognitive neuroscience is therefore the identification and monitoring of brain networks over short time durations(Hutchison et al., 2013), usually <1s for a picture naming task, for example. So far, few studies have addressed this issue which requires the use of techniques with a very high temporal resolution (of the order of the ms), which is the case for magneto- or electro-encephalography (MEG or EEG). However, the interpretation of connectivity measurements from recordings made at the level of the electrodes (scalp) is not simple because these recordings have low spatial resolution and their accuracy is impaired by volume conduction effects (Schoffelen and Gross, 2009). Thus, during recent years, the analysis of functional connectivity at the level of cortical sources reconstructed from scalp signals has been of increasing interest. The advantage of this method is to improve the spatial resolution, while maintaining the excellent resolution of EEG or MEG (Hassan et al., 2014; Hassan and Wendling, 2018; Schoffelen and Gross, 2009). However, the dynamic aspect has not been sufficiently exploited by this method. The first objective of this thesis is to show how the EEG connectivity approach source "makes it possible to follow the spatio-temporal dynamics of the cerebral networks involved either in a cognitive task or at rest. Moreover, recent studies have shown that neurological disorders are most often associated with abnormalities in cerebral connectivity that result in alterations in wide-scale brain networks involving remote regions (Fornito and Bullmore, 2014). This is particularly the case for epilepsy and neurodegenerative diseases (Alzheimer's, Parkinson's) which constitute, according to WHO, a major issue of public health.In this context, the need is high for new methods capable of identifying Pathological networks, from easy to use and non-invasive techniques. This is the second objective of this thesis
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Sajadian, Samar, e Alia Ibrahim. "Wireless Sensor Network Group Connectivity". Thesis, Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-14016.
Testo completoAbstract (sommario):
The importance of monitoring physical and environmental conditions increases day by day and, therefore, so is the necessity of having a reliable wireless sensor network (WSN). The need to overcome challenges in WSN deployment and operation arises due to WSN's nature and characteristics such as possible nodes' mobility, limited radio and processing power, available storage and physical effects of the environment (particularly harsh environments) and balancing energy consumption has motivated us to investigate solutions to those problems. By studying related work, it was possible to observe that techniques such as the use of a good link estimator and the deployment of a suitable topology are essential features for a WSN. The core idea is to capture link connectivity dynamically and use it on routing decisions to gain reliability and estimate the whole network connectivity. The three main steps for deployment of a reliable WSN are the following: - Link estimator - Routing and neighbor information - Suitable routing algorithms In addition, self-organization is an important capability that WSNs need to present. They should be reliable, scalable and energy efficient during the network lifetime and self-organization plays a key role in this context. Summing up all these aspects, it comes to the point that reliable connectivity is an important characteristic of a WSN. The goal of this work is to contribute with the research in the subject by means of implementing a suitable topology management and evaluating the network connectivity by the means of quantitative metric for the network as whole. Practical experiments results are presented and discussed.
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Rittman, Timothy. "Connectivity biomarkers in neurodegenerative tauopathies". Thesis, University of Cambridge, 2015. https://www.repository.cam.ac.uk/handle/1810/248866.
Testo completoAbstract (sommario):
The primary tauopathies are a group of neurodegenerative diseases affecting movement and cognition. In this thesis I study Progressive Supranuclear Palsy (PSP) and the Corticobasal Syndrome (CBS), two parkinsonian disorders associated with accumulation of hyperphos- phorylated and abnormally folded tau protein. I contrast these two disorders with Parkinson’s disease (PD), which is associated with the accumulation of alpha-synuclein but has a genetic association with the MAPT gene encoding tau. Understanding the tauopathies to develop effective treatments will require a better grasp of the relationships between clinical syndromes and cognitive measures and how the anatomical and neurochemical networks that underlie clinical features might be altered by disease. I investigate simple clinical biomarkers, showing that a two-minute test of verbal fluency is a potential diagnostic biomarker to distinguish between PD and PSP and that the ACE-R and its subscores could play a role in monitoring cognition over time in PD, PSP and CBS. I assess the implementation of network analysis in Functional Mag- netic Resonance Imaging (fMRI) data, introduce Maybrain software for graphical network analysis and visualisation. I go on to show an overlap between graph theory network measures and I identify three main factors underlying graph network measures of: efficiency and distance, hub characteristics, network community measures. I apply these measures in PD, PSP and the CBS. All three diseases caused a loss of functional connectivity in com- parison to the control group that was concentrated in more highly connected brain regions and in longer distance connections. In ad- dition, widely localised cognitive function of verbal fluency co-varied with the connection strength in highly connected regions across PD, PSP and CBS. To take this further, I investigated specific functional covariance networks. All three disease groups showed reduced connectivity between the basal ganglia network and other networks, and between the anterior salience network and other networks. Localised areas of increased co- variance suggest a breakdown of network boundaries which correlated with motor severity in PSP and CBS, and duration of disease in CBS. I explore the link between gene expression of the tau gene MAPT and its effects on functional connectivity showing that the expression of MAPT correlated with connection strength in highly connected hub regions that were more susceptible to a loss of connection strength in PD and PSP. I conclude by discussing how tau protein aggregates and soluble tau oligomers may explain the changes in functional brain networks. The primary tauopathies are a group of neurodegenerative diseases affecting movement and cognition. In this thesis I study Progressive Supranuclear Palsy (PSP) and the Corticobasal Syndrome (CBS), two parkinsonian disorders associated with accumulation of hyperphos- phorylated and abnormally folded tau protein. I contrast these two disorders with Parkinson’s disease (PD), which is associated with the accumulation of alpha-synuclein but has a genetic association with the MAPT gene encoding tau. Understanding the tauopathies to develop effective treatments will require a better grasp of the relationships between clinical syndromes and cognitive measures and how the anatomical and neurochemical networks that underlie clinical features might be altered by disease. I investigate simple clinical biomarkers, showing that a two-minute test of verbal fluency is a potential diagnostic biomarker to distinguish between PD and PSP and that the ACE-R and its subscores could play a role in monitoring cognition over time in PD, PSP and CBS. I assess the implementation of network analysis in Functional Mag- netic Resonance Imaging (fMRI) data, introduce Maybrain software for graphical network analysis and visualisation. I go on to show an overlap between graph theory network measures and I identify three main factors underlying graph network measures of: efficiency and distance, hub characteristics, network community measures. I apply these measures in PD, PSP and the CBS. All three diseases caused a loss of functional connectivity in com- parison to the control group that was concentrated in more highly connected brain regions and in longer distance connections. In ad- dition, widely localised cognitive function of verbal fluency co-varied with the connection strength in highly connected regions across PD, PSP and CBS. To take this further, I investigated specific functional covariance networks. All three disease groups showed reduced connectivity between the basal ganglia network and other networks, and between the anterior salience network and other networks. Localised areas of increased co- variance suggest a breakdown of network boundaries which correlated with motor severity in PSP and CBS, and duration of disease in CBS. I explore the link between gene expression of the tau gene MAPT and its effects on functional connectivity showing that the expression of MAPT correlated with connection strength in highly connected hub regions that were more susceptible to a loss of connection strength in PD and PSP. I conclude by discussing how tau protein aggregates and soluble tau oligomers may explain the changes in functional brain networks.
22
Ven, Vincent Gordon van de. "Connectivity and auditory verbal hallucinations". [Maastricht : Maastricht : Universiteit Maastricht] ; University Library, Maastricht University [Host], 2006. http://arno.unimaas.nl/show.cgi?fid=6557.
Testo completo
23
Eldh, Erik. "Cloud connectivity for embedded systems". Thesis, KTH, Kommunikationssystem, CoS, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-118746.
Testo completoAbstract (sommario):
Deploying an embedded system to act as a controller for electronics is not new. Today these kinds of systems are all around us and are used for a multitude of purposes. In contrast, cloud computing is a relatively new approach for computing as a whole. This thesis project explores these two technologies in order to create a bridge between these two wildly different platforms. Such a bridge should enable new ways of exposing features and doing maintenance on embedded devices. This could save companies not only time and money while dealing with maintenance tasks for embedded systems, but this should also avoid the needed to host this maintenance software on dedicated servers – rather these tasks could use cloud resources only when needed. This thesis explores such a bridge and presents techniques suitable for joining these two computing paradigms together. Exploring what is included in cloud computing by examining available technologies for deployment is important to be able to get a picture of what the market has to offer. More importantly is how such a deployment can be done and what the benefits are. How technologies such as databases, load-balancers, and computing environments have been adapted to a cloud environment and what draw-backs and new features are available in this environment are of interest and how a solution can exploit these features in a real-world scenario. Three different cloud providers and their products have been presented in order to create an overview of the current offerings. In order to realize a solution a way of communicating and exchanging data is presented and discussed. Again to realize the concept in a real-world scenario. This thesis presents the concept of cloud connectivity for embedded systems. Following this the thesis describes a prototype of how such a solution could be realized and utilized. The thesis evaluates current cloud providers in terms of the requirements of the prototype. A middle-ware solution drawing strengths from the services offered by cloud vendors for deployment at a vendor is proposed. This middle-ware acts in a stateless manner to provide communication and bridging of functionality between two parties with different capabilities. This approach creates a flexible common ground for end-user clients and reduces the burden of having the embedded systems themselves process and distribute information to the clients. The solution also provides and abstraction of the embedded systems further securing the communication with the systems by it only being enabled for valid middle-ware services.Att använda ett inbyggt system som en kontrollenhet för elektronik är inget nytt. Dessa typer av system finns idag överallt och används i vidt spridda användningsområden medans datormolnet är en ny approach för dator användning i sin helhet. Utforska och skapa en länk mellan dessa två mycket olika platformar för att facilitera nya tillvägagångs sätt att sköta underhåll sparar företag inte tid och pengar när det kommer till inbyggda system utan också när det gäller driften för servrar. Denna examensarbete utforskar denna typ av länk och presenterar för endamålet lämpliga tekniker att koppla dem samman medans lämpligheten för en sådan lösning diskuteras. Att utforska det som inkluderas i konceptet molnet genom att undersöka tillgängliga teknologier för utveckling är viktigt för att få en bild av vad marknaden har att erbjuda. Mer viktigt är hur utveckling går till och vilka fördelarna är. Hur teknologoier som databaser, last distrubutörer och server miljöer har adapterats till molnmiljön och vilka nackdelar och fördelar som kommit ut av detta är av intresse och vidare hur en lösning kan använda sig av dessa fördelar i ett verkliget scenario. Tre olika moln leverantörer och deras produkter har presenterats för att ge en bild av vad som för tillfället erbjuds. För att realisera en lösning har ett sett att kommunicera och utbyta data presenterats och diskuterats. Åter igen för att realisera konceptet i ett verkligt scenario. Denna uppsats presenterar konceptet moln anslutbarhet för inbyggda system för att kunna få en lösning realiserad och använd. En mellanprograms lösning som drar styrka ifrån de tjänster som erbjudas av molnleverantörer för driftsättning hos en leverantor föreslås. Denna mellanprogramslösnings agerar tillståndslöst för att erbjuda kommunikation och funktions sammankoppling mellan de två olika deltagarna som har olika förutsätningar. Denna approach skapar en flexibel gemensam plattform för olika klienter hos slutanvändaren och minskar bördan hos de inbyggdasystemet att behöva göra analyser och distrubuera informationen till klienterna. Denna lösning erbjuder också en abstraktion av de inbyggdasystemen för att erbjuda ytterligare säkerhet när kommunikation sker med de inbyggdasystemet genom att den endast sker med giltiga mellanprogram.
24
Waltersson, Roland. "Middleware for adaptive network connectivity". Thesis, KTH, Kommunikationssystem, CoS, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-92209.
Testo completoAbstract (sommario):
As the coverage of modern wireless technologies expands, today’s mobile phones and PDAs often have a range of heterogeneous networks to which they may connect. It would benefit mobile applications to use the network which best corresponds to its need. However, making the handovers between networks transparent to allow communication sessions to survive is not trivial as the TCP/IP suite, used by most networking applications today, was initially not designed with mobility in mind. A Vinnova founded research project at Saab (together with associates1) has found that it could prove advantageous to monitor network quality together with the application’s needs and make intelligent decisions regarding what network to use. An algorithm for network classification and evaluation has been proposed. This thesis examined prerequisites and methods for implementing adaptive network connectivity through transparent handovers for mobile devices, resulting in a tentative model to demonstrate the mentioned research results. The prototype, implemented as a user space middleware, utilizes UDP encapsulation and a per-packet basis link evaluation, resulting in small overhead and fast context adaptation. Link monitoring ensures that server and clients are constantly updated about network quality and availability. The prototype yielded transparent handovers between networks, with short handover delays, at the cost of reduced performance for fast networks. 1 Blekinge Institute of Technology, Swedish National Testing and Research Institute, and SwedishRoad AdministrationTäckningen av trådlösa nätverk ökar konstant, och dagens mobiltelefoner och handdatorer har ofta ett antal olika nätverk de kan ansluta till. Det skulle vara fördelaktigt för mobila applikationer att använda det nätverk som bäst passar dess behov. Att göra övergångarna mellan dessa nätverk transparenta så att pågående kommmunikationssessioner kan fortgå är dock inte helt trivialt, då TCP/IP protokollen från början inte var tänkta för mobila enheter. Ett av Vinnova finansierat forskningsprojekt utfört på Saab med flera1 har undersökt möjligheterna att övervaka kvaliteten på olika trådlösa nätverk samt kraven från applikationerna, och med detta som grund utföra intelligenta beslut om vilket nätverk som ska utnyttjas. En algoritm för att utföra dessa beslut har också föreslagits. Detta examensarbete undersökte möjligheterna för att implementera adaptiv nätverksroaming genom transparenta övergångar för mobila enheter, och resulterade i en demonstrator, som även kan visa resultaten från den nämnda forskningen. Prototypen, implementerad som en "middleware", använder UDP tunnling och en per-paket nätverksutvärdering, vilket resulterade i liten overhead och snabb anpassning till nya kommunikationssituationer. En länkövervakare såg till att server och klienter alltid var uppdaterade om kvaliteten och tillgängligheten av olika nätverk. Prototypen gav totalt transparenta övergångar mellan nätverk med relativt korta fördröjningar, med nackdelen av viss reducerad prestanda för snabba nätverk. 1 Blekinges Tekniska Högskola, Sveriges Provnings – och Forskningsinstitut, samt Vägverket
25
Zhao, Yiwen. "Livestock impacts on hydrological connectivity". Thesis, University of Leeds, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485753.
Testo completoAbstract (sommario):
In response to sustainable land management requirements and catchment-scale hydrological modelling needs, scientific interest in hydrological'connec~ivity'hasgrown. However, little is ~ . known about how hydrological connectivity is impacted by management. While there has been much research into livestock grazing and soil erosion in the UK; relatively little research has been conducted to characterize the hydrological patterns of livestock impacts, especially in organic soils which might be more vulnerable to environmental degradation. This thesis examines livestock impacts, as a land use case study, to conceptualize the 'dynamic nature of hydrological connectivity and its potential changes on hillslope and catchment hydrology. Different grazing strategies on organic soils (blanket p~ats and peaty gleys) in the uplands of Upper Wharfedale and Teesdale and organo-mineral soils (stagnogleys) in lowlands at Kirkby Overblow, northern England are investigated. Field measurements and monitoriIig are combined with laboratory experiments and proces~-based distributed modelling. Results suggest that compaction effects from sheep differ between soil types and topographic context but that they were generally confined to the upper 20 cm of the soil profile but with greater impacts in the upper 5 cm. Light-medium grazing (-9 a ha-1 ) significantly raised mean bulk density compared to adjacent soils with no grazing in the upper 10 cm of the soil profile of'stagnogleys. The relatively heavy grazing associated with frequently trampled areas under sheep tracks on stagnogleys was associated with soils with a mean bulk density 10 % greater (in the upper 10 cm of the soil) than those in the surrounding lightly grazed soil for stagnogleys, 2 % in 0-5 cm arid 9 % in 5-10 cm layers of peaty gleys, and at least 50 % in the near surface of peats. The effects of sheep tracks on soil properties and hydrological function were found to extend by at least 2 m further either side ofthe track rather than just being a feature ofthe visible track alone. Removing sheep led to a substantial fall in compaction effects in peats (10.4-21.7 % in bulk ~ensity) and stagnogley soils (0.5 % in bulk density) within a short time period (4-6 years). There were also significant differences in jnfiltration rates between short-term exclosure sites ' and grazed sites. For peat soils differences between lightly graZed areas and the long-term ' exclosures (35-45 years) were not much greater than those between the lightly grazed areas and the short-term exclosures suggesting that soil response to removal of sheep can be rapid. This thesis demonstrated that both the value and actual spatial distribution of livestock may .significantly decrease vertical connectivity and increase lateral connectivity, and hence increase both the spatial and temporal frequency of overland flow. In the organic soils of the humid-temperate zone studied this is through alteration of saturation-excess processes rather than infiltration-excess flow generation; antecedenfwater stores or soil moisture content are therefore of great, importance in hydrological connectivity responses to livestock impacts. Sheep tracks can be crucial in producing more rapid and connected overland flow on peats and stagnogleys, and effects extend several metres ether side of the track. Blanket peats are more vulnerable to livestock grazing than stagnogleys. The modelling approach used on stagnogleys from Kirkby Overblow suggests that increasing sheep density in very wet environments would lead to enhanced flood risks in terms of overall runoff amount and more rapid response due to e$anced coupling of hillslope arid river corridors, especially in extreme rainfall conditions.
26
Gray, Duncan Peter. "Ecological connectivity in braided riverscapes". Thesis, University of Canterbury. School of Biological Sciences, 2010. http://hdl.handle.net/10092/4181.
Testo completoAbstract (sommario):
Rivers are hierarchical networks that integrate both large and small scale processes within catchments. They are highly influenced by variation in flow and are characterised by strong longitudinal movement of materials. I conducted an extensive literature review that indicated braided rivers lie at the upper end of the river complexity gradient due to the addition of strong lateral and vertical connectivity with their floodplains. The management of these rivers requires an understanding of the connective linkages that drive complexity, however in developed regions few braided river systems remain intact. The large number of relatively pristine braided rivers in New Zealand provided a unique opportunity to study physical and biotic patterns in these large dynamic systems. Initially I examined horizontal connectivity through patterns in regional and local diversity in eleven braided rivers in the North and South islands of New Zealand. Subsequently, the next component of my thesis focused on vertical connectivity through intensive investigations of energy pathways and the recipient spring stream food-webs.
The eleven river survey included sampling of multiple reaches and habitats (main channels, side braids, spring sources, spring streams and ponds) and confirmed the importance of lateral habitats to invertebrate diversity. However, I found that large spatial scales made a greater contribution to diversity than small scales, such that major differences occurred between rivers rather than habitats. This result suggested either a role for catchment-scale factors, such as flow, or biogeographic patterning. Subsequent analysis of the relationships between invertebrate diversity and the physical environment indicated strong regulation by flow variability, but also biogeographic community patterns. Braided rivers are clearly disturbance dominated ecosystems, however the effects of disturbance are manifest in different ways across the riverscape.
The role of vertical hydrological connectivity in linking the different components of the floodplain was investigated by tracing carbon pathways from the terrestrial floodplain to spring-fed streams and their communities. Using δ13C isotope signatures it was possible to show that inorganic carbon in groundwater was derived from terrestrial vegetation and subsequently incorporated into spring stream food-webs. However, the degree to which a stream community uses groundwater as opposed to allochthonous carbon is affected by the successional stage of riparian vegetation, a function of the shifting habitat mosaic that is regulated primarily by flow variation and sediment dynamics. In summary, the structure of braided river ecosystems is regulated primarily at the catchment scale, but connectivity at smaller scales plays an important role in determining ecological structure and function.
27
Panigrahi, Debmalya. "Optimization problems in network connectivity". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78362.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (p. 115-120).
Besides being one of the principal driving forces behind research in algorithmic theory for more than five decades, network optimization has assumed increased significance in recent times with the advent and widespread use of a variety of large-scale real-life networks. The primary goal of such networks is to connect vertices (representing a variety of real-life entities) in a robust and inexpensive manner, and to store and retrieve such connectivity information efficiently. In this thesis, we present efficient algorithms aimed at achieving these broad goals. The main results presented in this thesis are as follows. -- Cactus Construction. We give a near-linear time Monte Carlo algorithm for constructing a cactus representation of all the minimum cuts in an undirected graph. -- Cut Sparsification. A cut sparsifier of an undirected graph is a sparse graph on the same set of vertices that preserves its cut values up to small errors. We give new combinatorial and algorithmic results for constructing cut sparsifiers. -- Online Steiner Tree. Given an undirected graph as input, the goal of the Steiner tree problem is to select its minimum cost subgraph that connects a designated subset of vertices. We give the first online algorithm for the Steiner tree problem that has a poly-logarithmic competitive ratio when the input graph has both node and edge costs. -- Network Activation Problems. In the design of real-life wireless networks, a typical objective is to select one among a possible set of parameter values at each node such that the set of activated links satisfy some desired connectivity properties. We formalize this as the network activation model, and give approximation algorithms for various fundamental network design problems in this model.
by Debmalya Panigrahi.
Ph.D.
28
Lammert, Emily Jane. "Repowering the void : negotiating connectivity". Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/43852.
Testo completoAbstract (sommario):
Thesis (M. Arch.)--Massachusetts Institute of Technology, Dept. of Architecture, 2008.Includes bibliographical references (p. 93-97).
Rejecting the conception of building as island as reflected in American obsession with detached currently reinforced by Zero Energy Building, the thesis explores patterns of connectivity. largely results from insular development and their related transportation modes. Further,' scales, when used at the building scale furthers an erroneous sense of self-sufficiency, suggested man energy consumption can be bounded by property lines. Therefore, the qualitative th housing) is a function of connectivity. The project explores and negotiates between connectivity ... and density in terms of a post-fordist shift from products to services. Using a large, empty ... initiates reconnection of the east side to the city center, where the need for connectivity. The project explores and negotiates between connectivity principles ecology, society, energy, and density in terms of a post-fordist shift from products to services. Using a large, commuter rail site in east Austin, TX, the project initiates reconnection of the east side to the city center, where the need for connectivity coalesces.
by Emily Jane Lammert.
M.Arch.
29
Carletti, Francesco. "Psychosis and cortico-cortical connectivity". Thesis, King's College London (University of London), 2013. http://kclpure.kcl.ac.uk/portal/en/theses/psychosis-and-corticocortical-connectivity(575f88df-15bc-4a85-8397-62e29cbc56c2).html.
Testo completoAbstract (sommario):
While psychotic disorders are thought to involve a disruption of cortico-cortical and cortico-subcortical connections, it is unclear whether this is a correlate of the disorder itself or is related to risk factors for the disorder. In this PhD thesis, I examined the integrity of cortical connections, the pattern of cortical morphology in two unique MRI datasets that have been collected over the last five years: one from a large sample of twins with and without schizophrenia, and another from a cohort of subjects with prodromal signs of psychosis, scanned before and after the onset of the disorder. The main hypothesis of this work is that abnormal cortical connectivity will be evident in subjects at risk of psychosis, but to a lesser degree than in patients with psychosis. Diffusion Tensor Imaging (DTI) and T1-weighted images were acquired for both samples. DTI is a brain imaging technique that aims to reconstruct white matter connections between cortical areas and assess their microstructure. T1-weighted imaging enables the examination of cortical shape changes that may result from abnormal connections. I applied to MRI data of both samples a voxel-brain morphometry analysis to DTI data, probabilistic tractography and a method for the assessment of cortical morphology. The principal result of my analysis confirmed the main hypothesis of this study. Further work revealed that abnormal connections are evident before the onset of psychosis and that these abnormalities may underlie the risk of developing psychosis.
30
Branco, Paulo José de Lemos. "Improving connectivity for river fish". Doctoral thesis, ISA, 2013. http://hdl.handle.net/10400.5/6447.
Testo completo
31
Castro, Maria Inês Fernandes. "Air connectivity and economic growth". Master's thesis, Instituto Superior de Economia e Gestão, 2020. http://hdl.handle.net/10400.5/20699.
Testo completoAbstract (sommario):
Mestrado em Economia Internacional e Estudos EuropeusO objetivo desta tese de Mestrado é estudar a correlação entre a conetividade aérea e algumas variáves que contribuem para o crescimento económico, e já mencionadas em estudos realizados anteriormente. Para atingir este objetivo, e relativamente aos dados da conetividade aérea, foi utilizado o modelo do Netscan. Os dados das variáveis económicas foram fornecidos pelo Banco Mundial e pela Eurostat. Os resultados empíricos desta tese, juntamente com as conclusões apresentadas na Revisão de Literatura, permitem-nos determinar que existe uma relação de causa-efeito entre a conetividade aérea e as variáveis económicas. Logo, a conetividade áerea pode contribuir para aumentar o crescimento económico dos países, nomeadamente da UE27. Em comparação com estudos realizados anteriormente, esta tese distingue os diferentes impactos que a conetividade do Aeroporto e a conetividade do Hub têm sobre as variáveis económicas que estão relacionadas com o crescimento ecomómico. Esta distinção é especialmente relevante ao nível da correlação entre a conetividade do Hub e o PIB, na medida em que a mesma é cada vez mais forte. Adicionalmente, este estudo utiliza dados específicos de aeroportos da União Europeia. É possível observar uma diferença significativa entre Portugal/Lisboa e os principais Hubs europeus. Desta forma, torna-se claro que Portugal deve aumentar a sua conetividade do Hub, que pode ser alcançada se for aproveitada a vantagem da sua localização geográfica, nomeadamente em relação aos continentes Americano e Africano. Assim, esta pode ser uma excelente oportunidade para Portugal conseguir alcançar um maior crescimento e desenvolvimento económicos.
This Master's thesis aims to study the correlation between air connectivity, and some economic variables, which contribute to economic growth already mentioned in previous researches. In order to achieve this goal, and regarding the air connectivity data, the Netscan model was used, developed by SEO Aviation Economics, in partnership with ACI (Airports Council International), World Bank, and Eurostat provided the economic variables' data. The empirical results of this thesis and the conclusions presented in the literature survey allow determining that there is a cause-effect relationship between air connectivity and the economic variables. Therefore, air connectivity can contribute to increase countries' economic growth, mainly the EU27. In comparison with previous research, this thesis distinguishes the different impacts that both airport connectivity and hub connectivity can have in economic variables related to growth. This distinction appears to be relevant as the correlation between Hub connectivity and Gross Domestic Product (GDP) is becoming stronger. In addition, this study is conducted using data for specific airports in the European Union. In the case of Portugal, we observe a very significant difference between Portugal/Lisbon and the main European hubs. With that in mind, it is clear that Portugal should increase its Hub connectivity, which could be achieved by taking advantage of its geographic position, mainly regarding the American and African continents. By doing so, it could be an exceptional opportunity for Portugal to achieve a higher economic development and growth.
info:eu-repo/semantics/publishedVersion
32
Santos, Wilson Bertino Lopes dos. "JDBC (Java DB connectivity) concorrente". Master's thesis, Universidade de Aveiro, 2011. http://hdl.handle.net/10773/7359.
Testo completoAbstract (sommario):
Mestrado em Engenharia de Computadores e TelemáticaA API JDBC permite aos programas Java manipularem dados de uma base de dados. No entanto, a definição da API não prevê uma utilização concorrente dos seus servi cos, n~ao e por isso poss vel partilhar objectos JDBC em seguran ca entre threads. Neste documento e descrita uma implementa c~ao concorrente da interface ResultSet. Esta interface e utilizada para ler ou modi car linhas do resultado da execu c~ao de uma instru c~ao SQL. O driver JDBC foi criado para SQL Server 2008. De modo a avaliar o desempenho da solu c~ao desenvolvida foram realizados testes de desempenho comparando-a com a implementa c~ao do driver da Microsoft, em que se criou um ResultSet por thread. Os resultados mostraram que a ideia desenvolvida produz um aumento de desempenho em ambientes multithreaded.
The JDBC API allows Java programs to access data stored on a data base. However, the API specification doesn't provide a solution for concurrent access to its interfaces, so it isn't safe to shared the same JDBC object between threads. This document describes the concurrent implementation of the Result Set interface. This interface is used to read or modify lines in the result of executing a SQL statement. The JDBC driver was created for SQL Server 2008. In order to assess its performance, the developed solution was benchmarked against the situation where it is created one ResultSet per thread using Microsoft's implementation of the JDBC driver. Results show that the solution increases performance on a multithreaded environment.
33
Hennayake, Kamal P. "Generalized edge connectivity in graphs". Morgantown, W. Va. : [West Virginia University Libraries], 1998. http://etd.wvu.edu/templates/showETD.cfm?recnum=383.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--West Virginia University, 1998.Title from document title page. Document formatted into pages; contains v, 87 p. : ill. Includes abstract. Includes bibliographical references (p. 64-72).
34
Nolan, Laura Patience. "Connectivity as an Evolutionary Step". Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/25887.
Testo completoAbstract (sommario):
This research is a multidisciplinary investigation into individual and collective disruptions of our time, which argues that the making and viewing of art is a vehicle for achieving harmony within ourselves. It acknowledges my personal experience as an echo of observed global disconnections and explores dysphoric catalysts such as industrialism, anthropocentrism, post- colonialism and agnosticism as causes for separation. This thesis examines the liminal spaces of making and experiencing art; regarding the making and viewing of art as a form of connecting to ourselves, one another and Presence, experienced as peace. I postulate the making processes of my art practice as a form of meditation where art making is undertaken as a mantra and my practice and process becomes prayer. Cocreating with invisible forces in an effort to imbue the works as votive objects I examine the prevalence of religion and ritual in cultures and draw from my personal spiritual experiences as a means of overcoming the limitations of my own power. This research draws on, yet is not limited to the work of artists and theorists on spirituality including theorists Georg Wilhelm Friedrich Hegel, Maurice Merleau-Ponty, Aldous Huxley, William James, Wassily Kandinsky, Joseph Beuys, Carl Jung, Martin Heidegger, Mihaly Csikszentmihalyi, Jane Bennett and Elizabeth Grosz and the environmental and political scholarship of Timothy Morton, Edward Said, Brian O’Doherty and artists working with ideas of disconnection and connection such as Fiona Hall, Lynda Benglis, Marina Abramovic, Abdul Abdullah, Yhonnie Scarce and Mark Rothko. I attempt to elucidate the transformative ability of the making process and the invaluable importance of connecting with ourselves, each other and Presence as a means of raising consciousness and ultimately, using art as a tool to evolve.
35
Stiefel, Maximilian. "IOT CONNECTIVITY WITH EDGE COMPUTING". Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-372094.
Testo completoAbstract (sommario):
Billions of Internet of Things (IoT) devices will be connected in the next decades. Most devices are for Massive Machine Type Communication (MMTC) applications. This requires the IoT infrastructure to be extremely efficient and scalable (like today’s Internet) to support more and more devices connected to the network over time. The cost per connection needs to be very low (like today’s Web services). The current network design with dedicated HW-based base stations (or IoT gateways) may be too costly. Furthermore, there is a vast amount of IoT radio standards, such as Narrowband-IoT (NB-IoT), LTE-M, BLE, ZigBee, Sigfox, LoRa, to give some examples, which all need to be implemented if they are supposed to be supported. The current approach requires to deploy parallel networks with dedicated base stations for different standards in one place. This further increases network costs. Cloud Radio Access Network (RAN) (c-RAN) has been proposed to centralize and cloudify baseband processing in a cloud infrastructure based on GPPs, which can potentially increase network flexibility and reduce the network Total Cost of Ownership (TCO) significantly. It can also be beneficiary for network performance by increased coordination possibilities. Nowadays, c-RAN still is on a concept level, because it is deemed difficult to implement due to complexity and reliability issues, e.g. for 4G/5G which requires sophisticated processing capabilities. The terminology of C-RAN today refers more to Centralized-RAN based on Digital Signal Processing (DSP) microcontrollers and ASICs, instead of c-RAN. However, the MMTC technologies are usually narrowband and designed with low complexity (considering cost of User Equipment (UE), power consumption, battery life time, etc.). Therefore, they are rather suitable for cloud implementation. Latency may be another issue for c-RAN. However, most of the MMTC applications are based on best-effort strategies and delay-tolerance. Therefore, c-RAN offers a promising solution to deliver the required efficiency and scalability for MMTC services. This master thesis is part of an effort to explore the possibilities, to increase the understanding and to gain hands-on experiences of IoT c-RAN implementation at the edge. It focuses on the NB-IoT downlink (DL) Physical (PHY) implementation as one example. However, IEEE 802.15.4 (PHY layer of e.g. Zigbee) has been integrated into the system within a collaboration between Ericsson and RISE SICS. This also shows, that c-RAN technology is able to unite multiple radio interfaces in one system leveraging Software (SW). In this study, we built a Software Defined Radio (SDR) testbed based on GNU Radio. The USRP B210 is the Hardware (HW) tool to test the implementation. Key components of the NB-IoT DL have been implemented. Orthogonal Frequency-Division Multiplex (OFDM) transmitter and receiver follow the NB-IoT numerology and implement algorithms for signal generation, time and frequency synchronization, as well as equalization and demodulation. The convolutional code of the Voyager missions with a coding rate R = 12 is used for performance evaluation. Different baseband modules have been tested and verified. Investigations have been carried out on the topic of latency. The measurements reveal a latency, which is higher than expected. Most likely, this is due to the large buffers underlying the GNU Radio scheduler in combination with the low speed of NB-IoT. The end-to-end system has been evaluated by field measurements (Signal-to-Noise Ratio (SNR), Bit Error Rate (BER), Packet Error Rate (PER)) conducted in an Ericsson office environment. With no Line-Of-Sight (LOS), the implemented system has a reach of >= 65 m (from the office lab on floor 4 to the other end of the corridor where GFTB ER NAP NIT Fronhaul Technologies is located) with only 0.5 % PER and a SNR of 15.9 dB. In this work, system and SW design of the testbed and implementation are presented, as well as the hands-on experiences. The testbed is ready for human interaction with a fascinating Telegram bot live demo.
36
Megas, Vasileios. "Aircraft to Aircraft Connectivity Analysis". Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254887.
Testo completoAbstract (sommario):
It is very common to feel the need to be connected, especially in cases where we are idle, such as in airplanes. Aircraft connectivity has already been implemented by using direct air-to-ground communication and satellite communication. However, since the current solutions are not satisfying, more ways to provide connectivity to aircraft are being researched. One solution is to use aircraft as relay nodes and forward signals to aircraft which are out of range of the ground base stations, creating an ad-hoc network.This thesis aims in evaluating the performance of such networks over the North Atlantic ocean in terms of connectivity and achievable data rate by means of simulations. First, an aircraft mobility model is created by analyzing past flight data. Then, the topology of the network is created with the purpose of maximizing the number of connected aircraft and minimizing interference. Finally, the available bandwidth is allocated to all connected aircraft in a maxmin way. The simulations were repeated to evaluate the impact of: threshold in data rates to assume connectivity, maximum number of connections per aircraft, maximum antenna steering angle, beamwidth and bandwidth.Our results show that aircraft to aircraft connectivity is feasible if all airlines cooperate, and more than 80% of the aircraft can find a path to a base station, when the aircraft density is higher than 1 aircraft per approximately 150000 km2, which is 88% of a 24 hours period. The median data rate of the connected aircraft, achieved in the middle of the ocean is limited to 25 Mbps with a 20MHz bandwidth, which is not high enough to provide access to demanding applications, such as video streaming. Increasing the bandwidth to 200 MHz can increase the data rate to more than 184 Mbps, for 50% of the connected aircraft, which surpasses the performance of current satellite communication systems.Det är ganska vanligt att känna behovet av att sammankopplas, särskilt i fall där vi är inaktiva, exempelvis i flygplan. Flygplansanslutning har redan implementerats genom att utnyttja direkt luft till markkommunikation och satellitkommunikation. Men eftersom de befintliga lösningarna inte är tillfredsställande, undersöks fler sätt att tillhandahålla anslutning till flygplan. En lösning är att använda flygplan som relä knutpunkter och framåtsignaler till flygplan som ligger utanför markbasen, skapar ett adhocnätverk.Den här avhandlingen syftar till att utvärdera prestanda för sådana nätverk över Nordatlanten när det gäller anslutning och uppnåelig datahastighet genom simuleringar. För det första frambringas en flygplansmobilitet genom att analysera tidigare flygdata. Därefter åstadkommas nätets topologi med syftet att maximera antalet anslutna flygplan och minimera störningar. Slutligen tilldelas den tillgängliga bandbredden till alla anslutna flygplan på maximal väg. Simuleringarna upprepas för att utvärdera effekten av: tröskeln i datahastigheter för att mottaga anslutning, maximalt antal anslutningar per flygplan, max antennstyrvinkel, strålbredd och bandbredd.Våra resultat visar att flygplan till flygplansförbindelser är genomförbart om alla flygbolag samarbetar och mer än 80% av flygplanet kan sammankoppla, när flygplansdensiteten är högre än 1 flygplan per ungefär 150000 km2. Median datahastigheten uppnådd i mitten av havet är begränsad till 25 Mbps med en 20 MHz bandbredd, vilket inte är tillräckligt hög för att bringa tillgång till krävande applikationer, såsom videostreaming. Ö kning av bandbredd till 200 MHz kan öka datahastigheten mer än 184 Mbps, för 50% av de anslutna flygplanen, vilketöverträffar prestanda för de nuvarande satellitkommunikationssystemen.
37
GRILLI, RUGGERO. "Markets connectivity and financial contagion". Doctoral thesis, Università Politecnica delle Marche, 2014. http://hdl.handle.net/11566/242842.
Testo completoAbstract (sommario):
Obiettivo di questo lavoro `e quello di analizzare l’impatto delle
diverse forme di interazione tra gli agenti economici, in relazione alle di-
namiche aggregate che si producono a livello sistemico.
I sistemi economici sono popolati da una moltitudine di agenti, tra loro etero-
genei, che prendono decisioni in contesti di informazione asimmetrica, il che
limita spesso la razionalit`a delle loro decisioni. I mercati non sono altro
che il luogo dove le decisioni individuali prendono la forma delle relazioni.
`E
dunque ammissibile rappresentare l’insieme delle relazioni che gli agenti
sviluppano all’interno di un mercato, attraverso l’uso delle reti, in cui i nodi
sono gli agenti economici e le cui connessioni sono le transazioni che vengono
sviluppate. Sul piano teorico, la rete delle transazioni rappresenta l’anello di
congiunzione tra la dimensione micro e quella macro. Da un lato, `e il luogo
dove si sviluppa l’interazione caotica tra gli agenti; dall’altro, a seconda delle
diverse forme dell’interazione individuale, la rete assume differenti strutture
aggregate, aventi differenti propriet`a sistemiche. In questo senso possiamo
affermare che le strutture aggregate emergono dall’interazione individuale e
che la dimensione macro non coincide con la somma della dimensione micro.
Nei modelli teorici che proponiamo, abbiamo analizzato le relazioni che gli
agenti stabiliscono reciprocamente nei mercati del credito e dell’interbancario.
Partendo dal comune incentivo a trarre profitti dalla propria attivit`a, abbi-
amo sperimentato diversi meccanismi di selezione del lender da parte dei borrowers
. Ognuno di essi caratterizza la distribuzione delle transazioni e quindi
la forma dell’interazione stessa. Siamo passati da un meccanismo di scelta
completamente random ad uno evolutivo legato alle performance individuali
degli agenti. Abbiamo studiato le propriet`a statistiche e di resilienza delle
strutture emergenti, confrontandole anche con l’impatto che producono in
termini di fluttuazioni del ciclo economico. La presenza di agenti eterogenei
ed interagenti crea fenomeni che ben riproducono i cicli macroeconomici em-
pirici. In particolare, evidenziano come il ciclo sia generato dall’eterogeneit`a
degli agenti nel sistema e non dalla magnitudo degli shock esogeni, che colpis-
cono l’economia. Se a ci`o aggiungiamo un meccanismo quale l’acceleratore
finanziario, i modelli presentati riescono anche a riprodurre dinamiche di cas-
cate di bancarotte, fenomeni ben evidenti soprattutto alla luce della presente
crisi economico finanziaria.The purpose of this work is to analyze the impact of different kind of interactions among economic agents on the aggregate dynamics of the system. Economic systems are usually populated by a wide set of heterogeneous agents, who take decisions in an asymmetric information environment, which, on turn, bounded the rationality of their choices. In this view, markets are the locus where individual decisions become relations among agents. It’s therefore possible to represent the set of agents’ relations through the use of networks, in which nodes are economic agents and links are the transactions played within the markets. From a theoretical point of view, the trading net- work is the bridge between the micro and macro dimensions. On one side, it is the place where agents’ chaotic interaction takes place; on the other side, depending on different kind of individual interaction, the network displays different aggregate structures, which have their diverse systemic properties. In this way, we can state that aggregate structures emerge from the individ- ual interaction and the macro dimension is not the mere sum of the micro behaviors. In the models we propose, we have analyzed the relations that agents mutu- ally establish on credit and interbank markets. From the common incentive to make profits from their activity, we have employed several lender selec- tion mechanisms from the borrowers’ side. Each of them characterizes the transaction distribution and therefore the form of interaction itself. We have gone from a fully random choice mechanism to an evolutionary one based on individual agent performances. We have studied statistical and resiliency properties of emergent structures, comparing them also respect to their im- pact in terms of business cycle fluctuations. The presence of heterogeneous interacting agents is able to create phenomena that reproduce the empiri- cal business cycles. In particular, this feature highlights that is the agents’ heterogeneity to generate the cyclical fluctuations rather than the exogenous shock’s magnitude, that hits the economy. If we also consider a mecha- nism, such as the financial accelerator, our models allow to replicate also bankruptcy cascade dynamics, as the recent financial crisis has shown.
38
Lindblom, Shari. "Audience connectivity in orchestral performances". Thesis, Queensland University of Technology, 2009. https://eprints.qut.edu.au/20533/1/Shari_Lindblom_Thesis.pdf.
Testo completoAbstract (sommario):
With the general global decline in the popularity and profitability of traditional orchestras, ways to build new audiences, develop new repertoires and create new networks and business partnerships are being explored. The aim of this thesis is to analyse the various elements of a proposed Orchestral Sustainability Framework and determine if and how these elements contribute to an increased audience connection with the music performance experience. Three main elements are explored in this Orchestral Sustainability Framework: 1. Social aspects of audience connection such as performer/audience interaction and ways of emotional engagement 2. Artistic aspects of audience connection such as the impact of poly-stylistic genres, blend of instruments and sounds and the importance of inter-sensory perception using visuals, theatre and music 3. Economic aspects of audience connection such as networking with business partnerships, impact of branding and marketing and the importance of distribution channels Audience reactions are central to this approach. Audiences from a variety of existing orchestral models have been researched through case studies, interviews, surveys, focus groups and participant observation. An orchestra, formed specifically for this project, performed to selected audiences and at the Brisbane Festival of Arts in 2006 and is now achieving commercialisation. The style of this orchestra is characterised by audience and performer interactivity, theatrical staging, visuals, spontaneity and less formality. Research has been conducted on this orchestral model, with contributions from the musicians, directors, producers, promoters and audiences. The research hypothesis proposes that a greater connectivity with the audience results in a more sustainable product, where sustainability is indicated by the orchestras’ ability to generate a sufficient amount of box office revenue and sponsorship. A variety of different models are considered which demonstrate orchestras that can achieve their mission of satisfying their audience, while being financial viable. The findings from the literature and the case studies clearly demonstrate the importance of many elements in the sustainability framework to achieve a greater level of audience connection with the orchestra.
39
Lindblom, Shari. "Audience connectivity in orchestral performances". Queensland University of Technology, 2009. http://eprints.qut.edu.au/20533/.
Testo completoAbstract (sommario):
With the general global decline in the popularity and profitability of traditional orchestras, ways to build new audiences, develop new repertoires and create new networks and business partnerships are being explored. The aim of this thesis is to analyse the various elements of a proposed Orchestral Sustainability Framework and determine if and how these elements contribute to an increased audience connection with the music performance experience. Three main elements are explored in this Orchestral Sustainability Framework: 1. Social aspects of audience connection such as performer/audience interaction and ways of emotional engagement 2. Artistic aspects of audience connection such as the impact of poly-stylistic genres, blend of instruments and sounds and the importance of inter-sensory perception using visuals, theatre and music 3. Economic aspects of audience connection such as networking with business partnerships, impact of branding and marketing and the importance of distribution channels Audience reactions are central to this approach. Audiences from a variety of existing orchestral models have been researched through case studies, interviews, surveys, focus groups and participant observation. An orchestra, formed specifically for this project, performed to selected audiences and at the Brisbane Festival of Arts in 2006 and is now achieving commercialisation. The style of this orchestra is characterised by audience and performer interactivity, theatrical staging, visuals, spontaneity and less formality. Research has been conducted on this orchestral model, with contributions from the musicians, directors, producers, promoters and audiences. The research hypothesis proposes that a greater connectivity with the audience results in a more sustainable product, where sustainability is indicated by the orchestras’ ability to generate a sufficient amount of box office revenue and sponsorship. A variety of different models are considered which demonstrate orchestras that can achieve their mission of satisfying their audience, while being financial viable. The findings from the literature and the case studies clearly demonstrate the importance of many elements in the sustainability framework to achieve a greater level of audience connection with the orchestra.
40
Rocchi, Federico. "Chemogenetic modulation of fMRI connectivity". Doctoral thesis, Università degli studi di Trento, 2022. http://hdl.handle.net/11572/335219.
Testo completoAbstract (sommario):
Resting-state fMRI (rsfMRI) has been widely used to map intrinsic brain network organization of the human brain both in health and in pathological conditions. However, the neural underpinnings and dynamic rules governing brain-wide rsfMRI coupling remain unclear. Filling this knowledge gap is of crucial importance, given our current inability to decode and reverse-engineer clinical signatures of aberrant connectivity into interpretable neurophysiological events that can help understand or diagnose brain disorders. Toward this goal, here we combined chemogenetics, rsfMRI, and in vivo electrophysiology in the mouse to investigate how regional manipulations of brain activity (i.e. neural inhibition, or excitation) causally contribute to whole-brain fMRI network organization. In a first set of proof of concept investigations, we empirically probed the widely held notion that neural inhibition of a cortical node would result in reduced fMRI coupling of the silenced area and its long-range terminals. Surprisingly, we found that chronic inhibition of the mouse medial prefrontal cortex (PFC) via viral overexpression of a potassium channel paradoxically increased fMRI connectivity between the inhibited area and its direct thalamo-cortical targets. Notably, acute chemogenetic inhibition of the PFC reproduced analogous patterns of fMRI overconnectivity. Using in vivo electrophysiology, we found that chemogenetic inhibition of the PFC enhances low frequency (0.1 - 4 Hz) oscillatory power via suppression of neural firing not phase-locked to slow rhythms, resulting in increased slow and δ band coherence between areas that exhibit fMRI overconnectivity. These results provide causal evidence that cortical inactivation can counterintuitively increase fMRI connectivity via enhanced, less-localized slow oscillatory processes, with important implications for neural modeling and interpretation of fMRI overconnectivity in brain disorders.
Importantly, our observation that neural inhibition of the PFC results in fMRI overconnectivity allowed us to predict that neural activation of the same area might produce opposite results, i.e. fMRI underconnectivity and neural desynchronization. To test this hypothesis, we used chemogenetics to increase local excitatory-inhibitory (E/I) balance in the PFC. As predicted, chemogenetic stimulation of CamkII-expressing neurons, or inhibition of fast-spiking parvalbumin-expressing neurons, produced similar rsfMRI signatures of rsfMRI underconnectivity. Both manipulations produced analogous electrophysiological signatures characterized by increased firing activity and a robust LFP power shift towards higher (i.e. γ) frequencies, effectively reversing the corresponding neural signature observed in DREADD inhibition studies. Importantly, the same E/I affecting perturbations were also associated with socio-communicative deficits in behaving mice hence underscoring the behavioral relevance of the employed manipulations. These results show that excitatory/inhibitory balance critically biases brain-wide fMRI coupling, pointing at a possible unifying mechanistic link between E/I imbalance and rsfMRI connectivity disruption in developmental disorders. More broadly, these investigations reveal a set of fundamental rules linking regional brain activity to macroscale functional connectivity, offering opportunities to physiologically interpret rsfMRI signatures of functional dysconnectivity in human brain disorders.
41
Almashaikhi, Talal. "Electrical brain stimulation and human insular connectivity". Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10174/document.
Testo completoAbstract (sommario):
Le cortex insulaire est le cinquième lobe du cerveau en charge de l'intégration de nombreuses fonctions cognitives, sous-tendues par une organisation cytoarchitectonique etune connectivité aussi riche que complexe. Ce travail vise à évaluer la connectivité fonctionnelle insulaire du cerveau humain par le biais de stimulation électrique intra-cérébrale et de potentiels évoqués cortico-corticaux (PECC) réalisés chez des patients explorés en stéréoélectroencéphalographie (SEEG) pour une épilepsie partielle réfractaire. Nous avons développé un protocole automatisé permettant destimuler successivement l’ensemble des bipoles d’enregistrement intracérébraux (deux plots contigus d’une même électrode) disponibles chez les patients explorés en SEEG. Deux sériesde 20 stimulations monophasiques d’une durée unitaire de 1 ms et d’une intentisté de 1 mA, étaient délivrés à une fréquence de 0,2 Hz au niveau de chaque bipole (105 en moyenne,produisant un total d’environ 11.000 PECC par patient). Un premier travail a consisté dans lamise au point d’une méthode fiable d’analyse statistique objective des PECC significatifs, encomplement de l’analyse visuelle, sur un échantillon de 33017 enregistrements chez trois patients. L’analyse a porté sur les quatre fenêtres temporelles post-stimulation suivantes: 10-100 ms, 100-300 ms, 300-500 ms, 500-1000 ms. La seconde partie de notre thèse a appliquéces méthodes à l’étude des connections intra-insulaires sur un échantillon de10 patients présentant au moins deux éléctrodes intra-insulaires. La dernière partie de notre travail s’est intéressé aux efférences insulaires sur un échantillon de 11 patients. L’étude des PECC apporte des éléments de connectivité fonctionnelle derésolution spatiale et temporelle inégalée, complémentaires de ceux découlant des techniquesde neuroimagerie. La gestion complexe du volume de données à gérer pour chaque patientpeut être résolu par des procédures d’analyse statistiques automatisée de sensibilité etspécificité satisfaisante. Le pattern des connections intra- et extra-insulaires révélé par cetteapproche permet une meilleure compréhension de la physiologie de l’insula chez l’Homme etdes modalités de propagations des décharges épileptiques impliquant ce lobeThe insular cortex is the fifth lobe of the brain and is in charge of the integration of many cognitive functions, underpinned by a rich cytoarchitectonic organization and a complex connectivity. Our work aims to evaluate the insular functional connectivity of the human brain using intracerebral electrical stimulation and recording of cortico-cortical evoked potentials (CCEPs) in patients investigated with stereoelectroencephalography (SEEG) for refractory partial epilepsy. We first developed an automated protocol to stimulate successively all intracerebral recorded bipoles (two contiguous leads of the same electrode) available in patients undergoing SEEG. Two sets of 20 monophasic stimulation of 1 ms duration and 1mA intensity were delivered at a frequency of 0.2 Hz at each bipole (105 on average, producing a total of about 11,000 recordings per patient). We then develop a reliable and objective statistical method to detect significant CCEPs as a complement to visual analysis, and validate this approach on a sample of 33017 recordings in three patients. The analysis was performed over four distinct post-stimulus epochs: 10-100 ms, 100-300 ms, 300-500 ms, 500-1000 ms. In the second part of our thesis, we applied these methods to the study of intrainsular connections on a sample of 10 patients with at least two intra-insular electrodes. The last part of our work used the same approach to investigate insular efferents in a sample of 11 patients. The study of CCEPs provides novel and important findings regarding the human brain functional connectivity, with unmatched spatial and temporal resolutions as compared to neuroimaging techniques. The complex management of large volume of data in each patient can be solved by automated statistical analysis procedures with satisfactory sensitivity and specificity. The pattern of connections within and outside the insula revealed by this approach provides a better understanding of the physiology of the Human insula as well as of the propagation of epileptic discharges involving this lobe
42
Goldhacker, Markus [Verfasser], e Elmar [Akademischer Betreuer] Lang. "Frequency-resolved dynamic functional connectivity and scale stability of connectivity-states / Markus Goldhacker ; Betreuer: Elmar Lang". Regensburg : Universitätsbibliothek Regensburg, 2017. http://d-nb.info/1124679944/34.
Testo completo
43
Margraf, Jeffrey A. "Decision support for network connectivity planning". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1996. http://handle.dtic.mil/100.2/ADA319588.
Testo completoAbstract (sommario):
Thesis (M.S. in Information Technology Management) Naval Postgraduate School, September 1996.Thesis advisor(s): S. Sridhar, H.K. Bhargava. "September 1996." Includes bibliographical references (p. 125). Also available online.
44
Ishii, Toshimasa. "Studies on Multigraph Connectivity Augmentation Problems". 京都大学 (Kyoto University), 2000. http://hdl.handle.net/2433/180897.
Testo completo
45
Nylén, Jan. "Exploring Ways of Visualizing Functional Connectivity". Thesis, Umeå universitet, Institutionen för tillämpad fysik och elektronik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-141182.
Testo completoAbstract (sommario):
Functional connectivity is a field within neuroscience where measurements of co-activation between brain regions are used to test various hypotheses or explore how the brain activates depending on a given situation or task. After analysis, the underlying data in the field consists of a n by n adjacency matrix where each cell represents a correlation value between two regions in the brain. Depending on the research question the number of regions and matrices incorporated varies and new visualizations are needed in order to portray them. In this thesis the design of an interactive web based visualization tool for functional connectivity was explored through an iterative design process. The design of the tool was based on existing guidelines, interviews and best practices in data visualization as well as an analysis of current visualization solutions used in functional connectivity. The final concept and prototype uses a network plot for functional connectivity called the connectogram as well as a grouped bar graph to provide an intuitive and accessible way of comparing functional connectivity data by interacting with and highlighting networks and specific network data through direct manipulation. Results of qualitative evaluations of a prototype using data from a concurrent scientific project is presented. The prototype was found to be useful, engaging, easily perceivable and offered an easy and quick way of exploring data sets.
46
Georganas, Nikita. "Car supplier and manufacturer connectivity issues". Thesis, University of Ottawa (Canada), 2004. http://hdl.handle.net/10393/26642.
Testo completoAbstract (sommario):
In today's fast pace society, analysts are expected to make quick educated decisions out of very complex situations. This is not an easy task to achieve but, if equipped with the proper decision tools, it can be effectively accomplished. Cognitive Maps have been commonly used in the past for this purpose but they lack a certain precision. Recently the use of Fuzzy Cognitive Maps (FCMs) has been proposed as an alternative for representing and analyzing complex systems that create outcomes that are not always easily definable. This thesis will introduce its readers to this versatile decision analysis tool and its many uses in a diversity of fields. More precisely, it will help analyze and determine how Internet transforms relationships between car parts suppliers and automobile manufacturers.
With the help of the Car Internet Research Program (CIRP), 17 semi-structured interviews of executive heads belonging to upstream suppliers in the automotive sector were considered as means of this research. Summarized and analysed through the help of FCMs, these exchanges give an approximate picture of the state of current events in the automotive industry, more precisely in regards to supplier and manufacturer connectivity issues.
47
Venigalla, Thejaswi, e Raj Kiran Akkapaka. "Teletraffic Models for Mobile Network Connectivity". Thesis, Blekinge Tekniska Högskola, Institutionen för kommunikationssystem, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-2441.
Testo completoAbstract (sommario):
We are in an era marked by tremendous global growth in mobile traffic and subscribers due to change in the mobile communication technology from second generation to third and fourth generations. Especially usage of packet-data applications has recorded remarkable growth. The need for mobile communication networks capable of providing an ever increasing spectrum of services calls for efficient techniques for the analysis, monitoring and design of networks. To meet the ever increasing demands of the user and to ensure on reliability and affordability, system models that can capture the characteristics of actual network load and yield acceptable precise predictions of performance in a reasonable amount of time must be developed. This can be achieved using teletraffic models as they capture the behaviour of system through interpret-able functions and parameters. Past years have seen extremely numerous teletraffic models for different purposes. Nevertheless there is no model that provides a proper frame work to analyse the mobile networks. This report attempts to provide a frame work to analyse the mobile traffic and based on the analysis we design teletraffic models that represent the realistic mobile networks and calculate the buffer under-flow probability.Vi är i en tid präglad av enorm global tillväxt inom mobil trafik och abonnenter på grund av förändringar i den mobila kommunikationsteknikenfrån andra generationen till tredje och fjärde led . Särskilt användningen av paketdataapplikationerhar spelat in en anmärkningsvärd tillväxt . Behovet av mobila kommunikationsnät som kan ge en allt större spektrum av tjänster lyser effektiva metoder för analys , övervakning och utformning av nät . För att möta de ständigt ökande kraven på användaren och för att säkerställa den tillförlitlighet och överkomliga priser , måste systemmodeller som kan fånga egenskaper faktiska belastningen på nätet och ger acceptabla precisa förutsägelser om prestanda i en rimlig tid att utvecklas . Detta kan uppnås med användning av teletrafik modeller som de fångar beteendet hos systemet genom tolka bara funktioner och parametrar . Tidigare år har sett väldigt många teletrafik modeller för olika ändamål . Det är likväl inte modellen som ger en ordentlig ramverk för att analysera de mobilnät. Rapporten försöker ge ett ramverk för att analysera mobiltrafik och baserat på analysen vi designar teletrafik modeller som representerar de realistiska mobilnät och beräkna buffertunderflödesannolikhet .
48
Wang, Chen. "Connectivity, Security and Integrationfor Cloud Manufacturing". Thesis, KTH, Industriell produktion, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-226522.
Testo completoAbstract (sommario):
Det här mastersprojektet syftar till att ansluta industriroboten till moln plattformen och utvärdera anslutning och säkerhet. För att uppnå bättre anslutning, säkerhet och integration, föreslås en modifierad Moln Tillverkningssystem- (CRS) arkitektur, som kännetecknas av hög modularitet, standardisering och komposibilitet. Arkitekturens specifika applikationer iprivata, offentliga och hybridmoln diskuteras också. Sedan är en systemarkitektur med detaljerad mjukvarukomposition designad för Molnrobotik. Enligt den föreslagna systemarkitekturen presenteras möjliga säkerhetshotskällor och motsvarande lösningar.Under projektet används Universell Robot 5 (UR5) som en praktisk robotinstans för att utveckla en kommunikationsrutin mellan KTH Moln och robotar. Ett applikationsprogramgränssnitt (API) skrivet i Python for Universell Robot och servern är etablerad. API: n består av två modulära delar, Gateway Agenten och Applikationsmjukvaran.Gateway Agenten realiserar kopplingen mellan Universell Robot 5 (UR5) och molnet, medan applikationsmjukvaran kan anpassas till specifika tillämpningar och krav. I detta projekt utvecklas tre huvudfunktioner i applikationsmjukvaran, inklusive datainsamling, datavisualisering och fjärrkontroll. Förutom att utvärdera anslutning och stabilitet simulerasdet privata robotik molnsystemet och det offentliga robotik molnsystemet med KTH Moln.Hybrid robotik moln systemet diskuteras också. Genom resultaten av fallstudier verifieras anslutningen och integrationen av Moln Tillverkningssystem.This master thesis project aims to connect the industrial robot to the Cloud platform, and evaluate the connectivity and security. To realize better connectivity, security and integration, a modified Cloud Manufacturing System (CRS) architecture is proposed, which is characterized by high modularity, standardization and composability. The architecture’s specific applications in private, public and hybrid cloud are discussed as well. Then, one system architecture with detailed software composition is designed for Cloud Robotics.According to the proposed system architecture, possible security threat sources and corresponding solutions are presented.During the project, Universal Robot 5 (UR5) is utilized as a practical robot instance to develop a communication routine between KTH Cloud and robots. An Application Program Interface (API) written by Python for Universal Robots and the server is established. The API consists of two modularized part, Gateway Agent and Application Package. The Gateway Agent realizes the connection between the Universal Robot 5 (UR5) and the cloud, while theApplication Package can be customized according to specific application and requirements. In this project, three main functions are developed in the Application Package, including data acquisition, data visualization and remote control. Besides, to evaluate connectivity and stability, private robotics cloud system and public robotics cloud system are simulated with KTH Cloud. The hybrid robotics cloud system is discussed as well. Through the results of case studies, the connectivity and integration of Cloud Manufacturing System are verified.
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Young, Clint Ernest. "Abnormal hippocampal synaptic connectivity in schizophrenia". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ61210.pdf.
Testo completo
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Cameron, Amy. "Approximation Algorithms for Network Connectivity Problems". Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/22734.
Testo completoAbstract (sommario):
In this dissertation, we examine specific network connectivity problems, and achieve improved approximation algorithm and integrality gap results for them. We introduce an important new, highly useful and applicable, network connectivity problem - the Vital Core Connectivity Problem (VCC). Despite its many practical uses, this problem has not been previously studied. We present the first constant factor approximation algorithm for VCC, and provide an upper bound on the integrality gap of its linear programming relaxation. We also introduce a new, useful, extension of the minimum spanning tree problem, called the Extended Minimum Spanning Tree Problem (EMST), that is based on a special case of VCC; and provide both a polynomial-time algorithm and a complete linear description for it. Furthermore, we show how to generalize this new problem to handle numerous disjoint vital cores, providing the first complete linear description of, and polynomial-time algorithm for, the generalized problem.
We examine the Survivable Network Design Problem (SNDP) with multiple copies of edges allowed in the solution (multi-SNDP), and present a new approximation algorithm for which the approximation guarantee is better than that of the current best known for certain cases of multi-SNDP. With our method, we also obtain improved bounds on the integrality gap of the linear programming relaxation of the problem. Furthermore, we show the application of these results to variations of SNDP. We investigate cases where the optimal values of multi-SNDP and SNDP are equal; and we present an improvement on the previously best known integrality gap bound and approximation guarantee for the special case of SNDP with metric costs and low vertex connectivity requirements, as well as for the similar special case of the Vertex Connected Survivable Network Design Problem (VC-SNDP).
The quality of the results that one can obtain for a given network design problem often depends on its integer linear programming formulation, and, in particular, on its linear programming relaxation. In this connection, we investigate formulations for the Steiner Tree Problem (ST). We propose two new formulations for ST, and investigate their strength in terms of their associated integrality gaps.