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1
Xia, Jianhong, i not supplied. "Modelling the spatial-temporal movement of tourists". RMIT University. Mathematical and Geospatial Sciences, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080110.161021.
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Tourism is one of the most rapidly developing industries in the world. The study of spatio-temporal movement models of tourists are undertaken in variety of disciplines such as tourism, geography, mathematics, economics and artificial intelligence. Knowledge from these different fields has been difficult to integrate because tourist movement research has been conducted at different spatial and temporal scales. This thesis establishes a methodology for modelling the spatial-temporal movement of tourists and defines the spatial-temporal movement of tourists at both the macro and micro level. At the macro level, the sequence of tourist movements is modelled and the trend for tourist movements is predicted based on Markov Chain theory (MC). Log-linear models are then adopted to test the significance of the movement patterns of tourists. Tourism market segmentation based on the significant movement patterns of tourists is implemented using the EM (Expectation-Maximisation) algorithm. At the micro level, this thesis investigates the wayfinding decision-making processes of tourists. Four wayfinding models are developed and the relationships between the roles of landmarks and wayfinding decision-making are also discussed for each type of the wayfinding processes. The transition of a tourist movement between the macro and micro levels was examined based on the spatio-temporal zooming theory. A case study of Phillip Island, Victoria, Australia is undertaken to implement and evaluate the tourist movement models established in this thesis. Two surveys were conducted on Phillip Island to collect the macro and micro level movement data of tourists. As results show particular groups of tourists travelling with the same movement patterns have unique characteristics such as age and travel behaviours such as mode of transport. Effective tour packages can be designed based on significant movement patterns and the corresponding target markets. Tourists with various age groups, residency, gender and different levels of familiarity with physical environment have different wayfinding behaviours. The results of this study have been applied to tourism management on Phillip Island and the novel methods developed in this thesis have proved to be useful in improving park facilities and services provided to tourists, in designing tour packages for tourism market promotion and in understanding tourist wayfinding behaviours.
2
Trukenbrod, Hans Arne. "Temporal and spatial aspects of eye-movement control : from reading to scanning". Phd thesis, Universität Potsdam, 2012. http://opus.kobv.de/ubp/volltexte/2014/7020/.
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Eye movements are a powerful tool to examine cognitive processes. However, in most paradigms little is known about the dynamics present in sequences of saccades and fixations. In particular, the control of fixation durations has been widely neglected in most tasks. As a notable exception, both spatial and temporal aspects of eye-movement control have been thoroughly investigated during reading. There, the scientific discourse was dominated by three controversies, (i), the role of oculomotor vs. cognitive processing on eye-movement control, (ii) the serial vs. parallel processing of words, and, (iii), the control of fixation durations.
The main purpose of this thesis was to investigate eye movements in tasks that require sequences of fixations and saccades. While reading phenomena served as a starting point, we examined eye guidance in non-reading tasks with the aim to identify general principles of eye-movement control. In addition, the investigation of eye movements in non-reading tasks helped refine our knowledge about eye-movement control during reading. Our approach included the investigation of eye movements in non-reading experiments as well as the evaluation and development of computational models.
I present three main results : First, oculomotor phenomena during reading can also be observed in non-reading tasks (Chapter 2 & 4). Oculomotor processes determine the fixation position within an object. The fixation position, in turn, modulates both the next saccade target and the current fixation duration. Second, predicitions of eye-movement models based on sequential attention shifts were falsified (Chapter 3). In fact, our results suggest that distributed processing of multiple objects forms the basis of eye-movement control. Third, fixation durations are under asymmetric control (Chapter 4). While increasing processing demands immediately prolong fixation durations, decreasing processing demands reduce fixation durations only with a temporal delay. We propose a computational model ICAT to account for asymmetric control. In this model, an autonomous timer initiates saccades after random time intervals independent of ongoing processing. However, processing demands that are higher than expected inhibit the execution of the next saccade and, thereby, prolong the current fixation. On the other hand, lower processing demands will not affect the duration before the next saccade is executed. Since the autonomous timer adjusts to expected processing demands from fixation to fixation, a decrease in processing demands may lead to a temporally delayed reduction of fixation durations. In an extended version of ICAT, we evaluated its performance while simulating both temporal and spatial aspects of eye-movement control.
The eye-movement phenomena investigated in this thesis have now been observed in a number of different tasks, which suggests that they represent general principles of eye guidance. I propose that distributed processing of the visual input forms the basis of eye-movement control, while fixation durations are controlled by the principles outlined in ICAT. In addition, oculomotor control contributes considerably to the variability observed in eye movements. Interpretations for the relation between eye movements and cognition strongly benefit from a precise understanding of this interplay.Blickbewegungen stellen ein wichtiges Instrument dar, um kognitive Prozesse zu untersuchen. In den meisten Paradigmen ist allerdings wenig über die Entstehung von Sakkaden und Fixationen bekannt. Insbesondere die Kontrolle der Fixationsdauern wurde häufig außer acht gelassen. Eine wesentliche Ausnahme stellt die Leseforschung dar, in der sowohl zeitlichliche als auch räumliche Aspekte der Blickbewegungssteuerung im Detail betrachtet wurden. Dabei war der wissenschaftliche Diskurs durch drei Kontroversen gekennzeichnet, die untersuchten, (i), welchen Einfluss okulomotorische bzw. kognitive Prozesse auf die Blicksteuerung haben, (ii), ob Worte seriell oder parallel verarbeitet werden und, (iii), wie Fixationsdauern kontrolliert werden. Die vorliegende Arbeit zielt im wesentlichen darauf ab, die Dynamik von Fixationssequenzen zu erforschen. Ausgehend von den Erkenntnissen beim Lesen untersuchten wir Blickbewegungen in Nichtlese-Aufgaben, mit dem Ziel allgemeine Prinzipien der Blicksteuerung zu identifizieren. Zusätzlich versuchten wir mit Hilfe dieser Aufgaben, Erkenntnisse über Prozesse beim Lesen zu vertiefen. Unser Vorgehen war sowohl von der Durchführung von Experimenten als auch der Entwicklung und Evaluation computationaler Modelle geprägt. Die Hauptbefunde zeigten: Erstens, okulomotorische Phänomene des Lesens lassen sich in Suchaufgaben ohne Wortmaterial replizieren (Kapitel 2 & 4). Dabei bestimmen okulomotorische Prozesse die Fixationsposition innerhalb eines Objektes. Diese wiederum beeinflusst das nächste Sakkadenziel sowie die Fixationsdauer. Zweitens, wesentliche Vorhersagen von Modellen, in denen Blickbewegungen von seriellen Aufmerksamkeitsverschiebungen abhängen, konnten falsifiziert werden (Kapitel 3). Stattdessen legen unsere Erkenntnisse nahe, dass die Blicksteuerung von der parallelen Verarbeitung mehrerer Objekte abhängt. Drittens, Fixationsdauern werden asymmetrisch kontrolliert (Kapitel 4). Während hohe Verarbeitungsanforderungen Fixationsdauern unmittelbar verlängern können, führen niedrige Verarbeitungsanforderungen nur zeitlich verzögert zu einer Reduktion. Wir schlagen ein computationales Modell ICAT vor, um asymmetrische Kontrolle zu erklären. Grundlage des Modells ist ein autonomer Zeitgeber, der unabhängig von der momentanen Verarbeitung nach zufälligen Zeitintervallen Sakkaden initiiert. Unerwartet hohe Verarbeitungsanforderungen können die Initiierung der nächsten Sakkade hinauszögern, während unerwartet niedrige Verarbeitungsanforderungen den Beginn der nächsten Sakkade nicht verändern. Der Zeitgeber passt sich allerdings von Fixation zu Fixation neuen Verarbeitungsanforderungen an, so dass es zu einer zeitlich verzögerten Reduktion der Fixationsdauern kommen kann. In einer erweiterten Version des Modells überprüfen wir die Kompatibilität ICATs mit einer realistischen räumlichen Blicksteuerung. Die Ähnlichkeit von Blickbewegungsphänomenen über Aufgaben hinweg legt nahe, dass sie auf allgemeinen Prinzipien basieren. Grundlage der Blicksteuerung ist die verteilte Verarbeitung des visuellen Inputs, während die Kontrolle der Fixationsdauer auf den Prinzipien von ICAT beruht. Darüber hinaus tragen okulomotorische Phänomene wesentlich zur Variabilität der Blicksteuerung bei. Ein Verständnis dieses Zusammenspiels hilft entscheidend den Zusammenhang von Blickbewegungen und Kognitionen besser zu verstehen.
3
Yasumiishi, Misa. "Spatial and temporal analysis of human movements and applications for disaster response management| Using cell phone data". Thesis, State University of New York at Buffalo, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1600848.
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This survey study examines cell phone usage data and focuses on the application of the data to disaster response management. Through the course of this study, the structure of cell phone usage data and its characteristics will be reviewed. Cell phone usage data provides us with valuable information about human movements and their activities. The uniqueness of the data is that it contains both spatial and temporal information and this information is free of fixed routes such as roads or any preset data capturing timing. In short, it is a very fluid kind of data which reflects our activities as humans with freedom of movement. Depending on data extraction methods, the data server can provide additional information such as application activities, battery level and charge activities. However, cell phone usage data contains shortcomings including data inconsistency and sparseness. Both the richness and the shortcomings of the data expose the hurdles required in data processing and force us to devise new ways to analyze this kind of data. Once the data has been properly analyzed, the findings can be applied to our real life problems including disaster response. By understanding human movement patterns using cell phone usage data, we will be able to allocate limited emergency resources more adequately. Even more, when disaster victims lose their cell phone functionality during a disaster, we might be able to identify or predict the locations of victims or evacuees and supply them with necessary assistance. The results of this study provide some insights to cell phone usage data and human movement patterns including the concentration of cell phone activities in specific zones and rather universal cell phone charging patterns. The potential of the data as a movement analysis resource and the application to disaster response is apparent. As a base to leverage the study to the next level, a possible conceptual model of human movement factors and data processing methods will be presented.
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van, Geel Catherina Francisca (Nienke). "Predator movements in complex geography : spatial distribution and temporal occurrence of low-density bottlenose dolphin communities off western Scotland". Thesis, University of the Highlands and Islands, 2016. https://pure.uhi.ac.uk/portal/en/studentthesis/predator-movements-in-complex-geography(f898982a-6509-4e73-9340-b0ad7463ae6d).html.
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The coastal waters off western Scotland are inhabited by two small under-studied common bottlenose dolphin (Tursiops truncatus) communities: the Inner Hebrides and the Sound of Barra (SoB) community. The region is considered for future developments for the marine renewables industry, which have the potential to negatively impact these communities; however the assessment of impacts and the development of plans to minimise these are currently hampered by a lack of knowledge about the dolphin's distribution and residency patterns, and spatial and temporal mobility. Using a variety of research methods (dedicated cetacean surveys and targeted photo-ID trips, acoustic monitoring and the collection of opportunistic photo-ID and sightings data from the general public) the current study examined local dolphin spatial and temporal mobility patterns by investigation of their spatial distribution and temporal occurrence. Collectively, the results revealed the presence of two socially and geographically separated (at least 2006-2013) resident communities which both demonstrated year-round presence and long-term site-fidelity, but maintained different ranging patterns. Long-term presence of individuals from the Inner Hebrides community dated back to 2001 and dolphins from this community ranged widely in nearshore waters throughout the entire currently known communal range, and practically used the entire range throughout the year. The SoB community, on the other hand, appeared to have a more restricted distribution, and appeared female-dominated. Summer censuses of the SoB community revealed annual estimates of ≤15 dolphins, with four individuals first identified in 1995, and at least eight calves born since 2005. Acoustic presence of dolphins in the SoB varied through the year, and in relation to the tidal and diel cycles. This study demonstrated that the integration of complementary methodological approaches is useful in investigating mobility patterns of low-density populations, and given the indications for social and spatial isolation, these communities should be managed independently.
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Levy, Manuel. "From boxes to codes : adaptation of V1 nonlinearities to the temporal encoding of spatial information during simuled eye movements". Paris 6, 2007. http://www.theses.fr/2007PA066238.
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Cette thèse a pour objet le rôle des nonlinéarités des cellules simples du cortex visuel primaire (V1) dans le traitement et l’encodage temporel des stimuli naturels. Les réponses neuronales enregistrées par des électrodes intra- et extra-cellulaires chez le Chat anesthésié et paralysé ont été analysées avec les outils de l’identification de système et de la théorie de l’information. Nous montrons que le recrutement des contrôles de gain au contraste et des interactions centre pourtour, en particulier par des stimuli dont la dynamique est dérivée des mouvement des yeux naturels, augmente la reproductibilité du potentiel de membrane dans les hautes fréquences ainsi que la précision temporelle et la rareté des potentiels d’action. Une inhibition de type complexe, en retard sur les entrées plus linéaires du neurone, modélise correctement nos résultats. Nous proposons que les nonlinéarités de V1 sont adaptées à l’encodage temporel d’une information spatiale de plus en plus détaillée durant le cours d’une fixation oculaireThis thesis focuses on the processing and temporal encoding of natural stimuli by simple cells of the primary visual cortex (V1). Neuronal responses were recorded by intra- and extra-cellular electrodes in the anaesthetized and paralysed Cat, and analysed with tools derived from system identification and information theory. We show that the recruitment of contrast gain controls and centre surround interactions, in particular by stimuli having natural eye movement dynamics, increases the reproducibility of the high temporal frequencies components of the membrane potential, as well as the temporal precision and sparseness of the spike output. The addition of a complex-like, feedforward, delayed inhibition to the classical LN model accounted largely for our results. Finally we propose that V1 nonlinearities are adapted to the coarse-to-fine processing and temporal encoding of spatial information during the course of an ocular fixation
6
Lättman, Håkan. "Description of spatial and temporal distributions of epiphytic lichens". Licentiate thesis, Linköping University, Linköping University, Department of Physics, Chemistry and Biology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-11561.
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Lichens are, in most cases, sensitive to anthropogenic factors such as air pollution, global warming, forestry and fragmentation. Two studies are included in this thesis. The first is an evaluation of the importance of old oak for the rare epiphytic lichen Cliostomum corrugatum (Ach.) Fr. This study analysed whether C. corrugatum was limited by dispersal or restricted to tree stands with an unbroken continuity or the substrate old oaks. The results provide evidence that the investigated five populations in Östergötland, Sweden, of C. corrugatum exhibit substantial gene flow, an effective dispersal and a small genetic variation between the sites. Most of the genetic variation was within the populations. Thus, C. corrugatum is more dependent of the substrate old oaks, rather than limited by dispersal. The second study investigated possible range shift of some common macrolichens, due to global warming, from 64 sites in southern Sweden comparing the two years 1986 and 2003. The centroid of three lichen species had moved a significant distance, all in a north east direction: Hypogymnia physodes (L.) Nyl. and Vulpicida pinastri (Scop.) J.-E. Mattsson and M. J. Lai on the tree species Juniperus communis L. (50 and 151 km, respectively) and H. physodes on Pinus sylvestris L. (41 km). Considering also the non-significant cases, there is strong evidence for a prevailing NE direction of centroid movement.
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Oslender, Ulrich. "Black communities on the Columbian Pacific coast and the 'aquatic space' : a spatial approach to social movement theory". Thesis, University of Glasgow, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366209.
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Knöll, Jonas [Verfasser], i Frank [Akademischer Betreuer] Bremmer. "Spatio-temporal representations during eye movements and their neuronal correlates / Jonas Knöll. Betreuer: Frank Bremmer". Marburg : Philipps-Universität Marburg, 2012. http://d-nb.info/1028072260/34.
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Nadorozny, Nicole Dorathea. "A temporal and spatial comparison of the movements of three frogs, genus Rana, among farm and forested landscapes in the Annapolis Valley, Nova Scotia". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq23697.pdf.
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Deck, Aubrey Lynn. "Spatio-temporal relationships between feral hogs and cattle with implicatons for disease transmission". Texas A&M University, 2003. http://hdl.handle.net/1969.1/5884.
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It is widely recognized that livestock industries are vulnerable to intentional or
accidental introductions of Foreign Animal Diseases (FADs). Combating disease is
difficult because of unknown wildlife-livestock interactions. Feral hogs (Sus scrofa)
could harbor and shed disease in areas used by domestic livestock such as cattle (Bos
taurus). Extent of risk logically depends on spatio-temporal interactions between
species. I used Global Positioning System (GPS) collars on cattle and hogs in
combination with a Geographic Information Systems (GIS) for detailed analysis on
movement patterns of these 2 species on a ranch in southwestern Texas, USA.
Motion-triggered video recorders were also utilized to determine interspecific activity
patterns. I tested hypotheses that spatio-temporal distributions of domestic cattle and
feral hogs on rangeland overlap and that interspecific contact occurs. If these posits are
true, it is possible that introduced pathogens like foot-and-mouth disease (FMD) could
be transmitted from feral hogs to cattle.
Using a rate of 1 GPS fix/15 min (96 fixes/day), I found that spatial distribution
of individual hogs and cattle overlapped on both the 95% and 50% kernel area use among 4 seasons. Both cows and feral hogs used Clay Flat, Clay Loam, and Rolling
Hardland more so than other range sites. During Summer 2004, riparian zones were the
most used feature, identified at 14% (2,760/19,365) of cattle and 70% (445/632) of hog
fixes. Other than brush strips, cattle and feral hogs primarily interacted at riparian zones,
fencelines, and roads. There were no direct interspecific contacts evident from GPS
data, but 3 cases were recorded from video data. Indirect interspecific contacts that may
be sufficient for disease transmission occurred much more frequently (GPS = 3.35
indirect contacts/day, video = cows follow hogs: 0.69 indirect contacts/day and hogs
follow cows: 0.54 indirect contacts/day). Research results suggested that both species
often travel along the same roads and fencelines to water and food sources, especially
during extreme heat and low-precipitation conditions. This research provides basic
information needed to improve models for management of FAD outbreaks in the U.S.,
based on specific knowledge of landscape usage and movement patterns of feral hogs
and cattle.
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Sobreiro, Filho José [UNESP]. "Contribuição à construção de uma teoria geográfica sobre movimentos socioespaciais e contentious politics: produção do espaço, redes e lógica-racionalidade espaço-temporal no Brasil e Argentina". Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/143908.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Neste trabalho, apresentamos um conjunto de reflexões cujo objetivo é de contribuir para a construção de uma teoria geográfica sobre movimentos socioespaciais e contentious politics. Assim, partimos dos principais conceitos geográficos (espaço, território, rede, lugar e escala) e das reflexões sobre movimentos socioespaciais e socioterritoriais, contentious politics, socio-spatial posicionality, convergence space e terrains of resistance, bem como da teoria da produção do espaço, para apresentar um modelo explicativo eminentemente geográfico. Tempo e espaço apresentam-se indissociáveis desde o remontar histórico dos conflitos até a própria análise dos conflitos contemporâneos. Por fim, o desfecho deste trabalho tem a nossa contribuição teórica, denominada por lógica-racionalidade espaço-temporal, lastreada na análise movimentos socioespaciais e casos de contentious politics no Brasil e Argentina.
In this thesis, we present a set of reflections whose objective is to contribute to the construction of a geographical theory of socio-spatial movements and contentious politics. Hence we set out and use the key geographical concepts (space, territory, network, place and scale) and reflections on socio-spatial and socio-territorial movements, contentious politics, socio-spatial positionality, convergence space and terrains of resistance, as well as the theory of production of space to present an eminently geographic explanatory model. Time and space are presented as inseparable from the history of the conflict as well in the analysis of contemporary conflicts. Finally, the outcome of this work is our theoretical contribution, called spatial-time logic-rationality, based in the analysis of the socio-spatial movements and cases of contentious politics in Brazil and Argentina.
FAPESP: 2013/22180-0
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Ridefelt, Hanna. "Spatial and Temporal Variations of Solifluction and Related Environmental Parameters in the Abisko Mountains, Northern Sweden". Doctoral thesis, Uppsala universitet, Institutionen för geovetenskaper, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-101419.
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This thesis presents an assessment of the variation in solifluction occurrence, morphometry and movement rates in the Abisko region, northern Sweden. Variations in movement rates are analyzed both on a regional and local scale. The main methodological contributions of this thesis have been to provide new techniques of analyzing spatial and temporal variations of solifluction in order to detect long term temporal trends and to regionalize the variations in movement rates. The spatial analysis is achieved by using a combination of field measurements, GIS and remote sensing techniques and statistical analysis. The results are presented in six papers, focusing on the morphometry of solifluction landforms (paper I), the occurrence of permafrost (paper II), the spatial and temporal variations of lobe front movement rates using aerial photographs (paper III), the temporal, regional and local spatial variations in movement rates (paper IV – VI) and statistical modelling of the occurrence of solifluction landforms and calculation of geomorphic work (paper V and VI). The results show that, on a regional scale, vegetation patterns are a major control on the occurrence of turf-banked solifluction landforms, with high NDVI-values (vegetation) associated with the presence of forms. Elevation is also a major control on a regional scale with a decrease in lobe dimensions and movement rates with increased elevation. High soil moisture values are associated with larger landforms and increased movement rates. Movement rates are generally higher in the western part of the region and appear to increase with higher MAAT. Equally, geomorphic work is greatest in the western part of the region. The important controls on a local scale vary from site to site, but include vegetation, slope angle and soil moisture. The photo analysis indicates that annual movement rates of lobe fronts in Kärkevagge and Låktatjåkka valley over the period 1959-2000 ranges from not-detectable to 63mm/yr. The permafrost model shows probabilities >0.8 for permafrost at elevations above 1300 m a.s.l. in the western part of the region, decreasing to altitudes over 850 m a.s.l. in the eastern part of the region. Calculated geomorphic work suggests that solifluction is a significant denudational agent in the sub-Arctic mountains of northern Sweden, but less so than previously estimated.
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Trukenbrod, Hans A. [Verfasser], i Ralf [Akademischer Betreuer] Engbert. "Temporal and spatial aspects of eye-movement control : from reading to scanning / Hans Arne Trukenbrod. Betreuer: Ralf Engbert". Potsdam : Universitätsbibliothek der Universität Potsdam, 2014. http://d-nb.info/1049586387/34.
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Nemoto, Keiichi. "Modeling the impacts of area closures on the Hawaii longline fishery a spatial-temporal economic model incorporating fish movement /". Thesis, University of Hawaii at Manoa, 2002. http://proquest.umi.com/pqdweb?index=1&did=765044511&SrchMode=1&sid=3&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1209150203&clientId=23440.
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Simoncini, Claudio. "Intégration spatio-temporelle de l'information visuelle pour les mouvements oculaires et la perception : =Spatio-temporal integration of visual information for eye movements and perception". Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM5065/document.
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Dans ce travail de thèse, nous avons tout d’abord étudié comment l’information de mouvement est intégrée pour estimer la vitesse d’une texture aléatoire afin de la suivre réflexivement avec les yeux ou d’estimer perception son déplacement. Dans une seconde série d’études, nous avons étudié comment la distribution spatiale du contraste dans une texture affecte à la fois les mouvements oculaires de fixation et la reconnaissance perceptive. A ces fins, nous avons utilisé un nouvel ensemble de stimuli visuels, des textures pseudo-naturelles dans lesquelles on peut finement contrôler la statistique (moyenne, variance) des fréquences spatiales et/ou temporelles. La première partie explore l’intégration et le décodage de information fréquentielle spatio-temporelle visuelle pour les réponses de poursuite réflexes et la discrimination perceptive. Nous montrons que l’action tire complètement partie de la richesse du stimuli en intégrant sur toute la distribution pour estimer la vitesse : accélération initiale, précision et robustesse sont améliorées. Au contraire, la performance perceptive décroit pour des stimuli à bandes passantes larges. Cette dissociation se maintient sur une large place d’intégration temporelle. La seconde partie élargie cette approche à la distribution spatiale de l’information et à ces différentes échelles. Nous montrons que le comportement oculaire de fixation dépend de la composition fréquentielle d’une texture, en termes de moyenne et de fréquence. Saccade et micro-saccades se distribuent au cours de la fixation de façon coordonnée en fonction de cette statistique. In fine, cette dernière joue sur la carte de salience calculée à partir de l’imageWe focused on the impact of the statistical distributions of visual information on these various behavioral responses. We asked first how motion information is integrated to estimate speed in order to perform either a speed discrimination task or to control reflexive tracking eye movements. Next, we investigated how spatial distribution in textures affects both pattern recognition and fixational eye movements. To do so, we used a set of artificial stimuli that are naturalistic textures where we can maintain a tight control on their information contents as for instance their spatio-temporal frequency bandwidth. The first studies compared speed information decoding for ocular following eye movements and perceptual speed discrimination. We found a strong dissociation where ocular following take full advantage by the enlargement of the spatio-temporal frequency bandwidth while perceptual speed discrimination is largely impaired for large bandwidth stimuli. Such dissociation remains over a large temporal integration window. We propose an adaptive gain control mechanism to explain this opposite dependencies. The second series of experimental studies investigate the properties of fixation eye movements (microsaccade and saccade) as a function of the mean and variance of the spatial frequency content of visual static textures. We show that several characteristics of fixational saccades (location, direction and amplitude) varied systematically with the distribution of spatial frequencies. The spatial distribution of the fixation zones could be best predicted from the saliency maps of the stimuli
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Frey, Margo Tilley. "Development of a Substrate with Photo-Modulatable Rigidity for Probing Spatial and Temporal Responses of Cells to Mechanical Signals: A Dissertation". Digital WPI, 2008. https://digitalcommons.wpi.edu/etd-dissertations/337.
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"Topographical and mechanical properties of adhesive substrates provide important biological cues that affect cell spreading, migration, growth, and differentiation. The phenomenon has led to the increased use of topographically patterned and flexible substrates in studying cultured cells. However, these studies may be complicated by various limitations. For example, the effects of ligand distribution and porosity are affected by topographical features of 3D biological constructs. Similarly, many studies of mechanical cues are compounded with cellular deformation from external forces, or limited by comparative studies of separate cells on different substrates. Furthermore, understanding cell responses to mechanical input is dependent upon reliable measurements of mechanical properties. This work addresses each of these issues. To determine how substrate topography and focal adhesion kinase (FAK) affect cell shape and movement, I studied FAK-null (FAK -/-) and wild type mouse 3T3 fibroblasts on chemically identical polystyrene substrates with either flat surfaces or micron-sized pillars, I found that, compared to cells on flat surfaces, those on pillar substrates showed a more branched shape, an increased linear speed, and a decreased directional stability, which were dependent on both myosin-II and FAK. To study the dynamic responses to changes in substrate stiffness without other confounding effects, I developed a UV-modulatable substrate that softens upon UV irradiation. As atomic force microscopy (AFM) proved inadequate to detect microscale changes in stiffness, I first developed and validated a microsphere indentation method that is compatible with fluorescence microscopy. The results obtained with this method were comparable to those obtained with AFM. The UV-modulatable substrates softened by ~20-30% with an intensity of irradiation that has no detectable effect on 3T3 cells on control surfaces. Cells responded to global softening of the substrate with an initial retraction followed by a gradual reduction in spread area. Precise spatial control of softening is also possible - while there was little response to posterior softening, anterior softening elicited a pronounced retraction and either a reversal of cell polarity or a significant decrease in spread area if the cells move into the softened region. In conclusion, these techniques provide advances in gaining mechanistic insight into cellular responses to topographical and mechanical cues. Additionally, there are various other potential applications of the novel UV-softening substrate, particularly in regenerative medicine and tissue engineering. "
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Okazaki, Victor Hugo Alves. "Controle de movimentos rápidos e precisos direcionados a alvos espaciais". Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/39/39132/tde-05062009-080327/.
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Neste estudo foi analisado o efeito de distância, velocidade, tamanhos do disco e do alvo, e massas do disco e da manopla, sobre o desempenho motor em movimentos requisitando rapidez e precisão. Para tanto, foram analisadas as características cinemáticas da tarefa de projetar um disco a um alvo com movimento de contato balístico, empunhando uma manopla. Os movimentos foram desempenhados sobre uma base plana e filmados com câmera optoeletrônica de alta freqüência. O estudo foi conduzido em seis experimentos com um grupo único de participantes. Os resultados indicaram que os modelos de controle motor que têm sido empregados para analisar a relação velocidade-precisão em tarefas mais simples não foram apropriados para explicar o comportamento da tarefa utilizada. O controle motor na tarefa demonstrou ser dinâmico e flexível, frente às diferentes restrições de movimento. As seguintes estratégias de controle foram sugeridas na explicação dos resultados: sincronização da maior velocidade e do instante de contato manopla-disco, manutenção na proporção entre as fases aceleração-desaceleração, maior inércia e menor impacto para aumentar a estabilidade de movimento, e o controle da velocidade e da precisão em dimensões independentes. A análise das ações articulares demonstrou as particularidades das estratégias utilizadas pelo sistema no movimento em função das variáveis manipuladas. Em conjunto, esta seqüência de experimentos permitiu uma compreensão mais ampla das estratégias de controle motor empregadas em movimentos com alta demanda de velocidade e de precisãoIn this study it was analyzed the effect of distance, velocity, disc and target width, disc and manipulandum mass, over motor control of a rapid and accurate movement. For such, it was analyzed the kinematic characteristics of the task of launching a disc to a target using a ballistic movement, performed with a manipulandum. Movements were performed on a flat surface and filmed with a high frequency optoelectronic camera. The study was conducted through six experiments with a single group of participants. Analysis of results indicated that models of motor control that has been used to analyze speed-accuracy tradeoff in simpler tasks were not appropriate to explain the observed behavior in the task used. Motor control in the task showed to be dynamic and flexible, regarding the several constraints manipulated. The follow strategies of control were suggested to explain the results: synchronization of the peak velocity and the instant of disc-manipulandum contact, maintenance of the proportion between the acceleration-deceleration phases, greater inertia and minor impact to increase movement stability, and control of velocity and accuracy of independent dimensions. The prediction of Analysis of joint actions showed the particularities of the strategies used by the system on movement as a function of the manipulated variables. Together, this study sequence of experiments allowed for a deeper comprehension of the control strategies used in the control of rapid and accurate movements
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Davison, Adrian Keith. "Micro-facial movement detection using spatio-temporal features". Thesis, Manchester Metropolitan University, 2016. http://e-space.mmu.ac.uk/617106/.
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Micro-facial expressions are fast, subtle movements of facial muscles that occur when someone is attempting to conceal their true emotion. Detecting these movements for a human is di�cult, as the movement could appear and disappear within half of a second. Recently, research into detecting micro-facial movements using computer vision and other techniques has emerged with the aim of outperforming a human. The motivation behind a lot of this research is the potential applications in security, healthcare and emotional-based training. The research has also introduced some ethical concerns on whether it is okay to detect micro-movements when people do not know they are showing them. The main aim of this thesis is to investigate and develop novel ways of detecting micro-facial movements using features based in the spatial and temporal domains. The contributions towards this aim are: an extended feature descriptor to describe micro-facial movement namely Local Binary Patterns on Three Orthogonal Planes (LBP-TOP) combined with Gaussian Derivatives (GD); a dataset of spontaneously induced micro-facial movements, namely Spontaneous Activity of Micro-Movements (SAMM); an individualised baseline method for micromovement detection that forms an Adaptive Baseline Threshold (ABT); Facial Action Coding System (FACS)-based regions are proposed to focus on the local movement of relevant facial areas. The LBP-TOP with GD feature was developed to improve on an established feature and use the GD to enhance the facial features. Using machine learning, the method performs well achieving an accuracy of 92.6%. Next a new dataset, SAMM, was introduced that improved on the limitations of previous sets, including a wider demographic, increased resolution and comprehensively FACS coded. An individualised baseline method was the introduced and tested using the new dataset. Using feature di�erence instead of machine learning, the performance increased with a recall of 0.8429 on the maximum thresholding and a further increase of the recall to 0.9125 when using the ABT. To increase the relevance of what is being processed on the face, FACS-based regions were created. By focusing on local regions and individualised baselines, this method outperformed similar state-of-the-art with an Area Under Curve (AUC) of 0.7513. The research into detecting micro-movements is still in it's infancy, and much more can be done to advance this �eld. While machine learning can �nd patterns in normal facial expressions, it is the feature di�erence methods that perform the best when detecting the subtle changes of the face. By using this and comparing the movement against a person's baseline, the micro-movements can �nally be accurately detected.
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Zapletal, Dominik. "Preemptivní bezpečnostní analýza dopravního chování z trajektorií". Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2018. http://www.nusl.cz/ntk/nusl-385900.
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This work deals with the and preemptive road users behaviour safety analysis problem. Safety analysis is based on a processing of road users trajectories obtained from processed aerial videos captured by drons. A system for traffic conflicts detection from spatial-temporal data is presented in this work. The standard approach for pro-active traffic conflict indicators evaluation was extended by simulating traffic objects movement in the scene using Ackerman steering geometry in order to get more accurate results.
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Parker, Austin. "Spatial probabilistic temporal databases". College Park, Md.: University of Maryland, 2008. http://hdl.handle.net/1903/8728.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2008.Thesis research directed by: Dept. of Computer Science. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Worton, B. J. "Statistical modelling of spatial animal movements". Thesis, University of Kent, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234980.
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Storey, Susan. "Spatial-temporal fish stock assessment". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ28463.pdf.
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Slack, Marc G. "Spatial and temporal path planning". Thesis, This resource online, 1987. http://scholar.lib.vt.edu/theses/available/etd-04272010-020255/.
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Liu, Fang 1962. "Modeling spatial and temporal textures". Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/29131.
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Henderson, Jonathan. "Avian spatial and temporal cognition". Thesis, University of Edinburgh, 2004. http://hdl.handle.net/1842/14049.
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I investigated the spatial memory abilities of male rufous hummingbirds (Selasphorus rufus) on their breeding grounds, where birds can be readily trained to feed from artificial flowers presented in two- and three-dimensional arrays. I found that birds use height as a cue when encoding flower locations, preferring to visit taller flowers. Performance in three-dimensional arrays was not however consistently better than in 2-D arrays. I also examined the possibility that hummingbirds follow a fixed flight path when returning to an array of flowers, as has been seen in the Hymenoptera. By manipulating the number of doors by which a bird could enter an arena to feed on an array of flowers, I found some evidence that birds do use systematic movements when relocating rewarding sites. Rufous hummingbirds feed on floral nectar, a resource that varies in time as well as space. To determine whether these birds use time as a cue when foraging, I provided them with an array in which flowers were refilled after intervals of either ten or twenty minute. The birds were able to learn these intervals, as they returned to flowers on or shortly after their expected refill time. I used an analogous experiment to investigate timing abilities in coal tits (Parus ater), a food-storing species, and great tits (P. major), a non food-storing species, in the laboratory. Storers and non-storer might differ in their ability to time intervals due to the demands, on storers, of reliable cache recovery. Coal tits were able to track the availability of rewards in three different locations associated with reward schedules in the 30-120s range. I found no consistent differnces in the abilities of coal tits and great tits to time intervals in the 40-70s range. In conclusion, rufous hummingbirds were shown to use both spatial and temporal cues whilst foraging at flowers. Coal tits and great tits were able to time short intervals in the laboratory, but I found no overall differences in timing behaviour between the two species.
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Kovalenko, Lyudmyla. "The temporal interplay of vision and eye movements". Doctoral thesis, Humboldt-Universität zu Berlin, Lebenswissenschaftliche Fakultät, 2016. http://dx.doi.org/10.18452/17507.
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Das visuelle System erreicht enorme Verarbeitungsmengen, wenn wir unsere Augen auf ein Objekt richten. Mehrere Prozesse sind aktiv bevor unser Blick das neue Objekt erreicht. Diese Arbeit erforscht die räumlichen und zeitlichen Eigenschaften drei solcher Prozesse: 1. aufmerksamkeitsbedingte Steigerung der neuronalen Aktivität und sakkadische Suppression; 2. aufmerksamkeitsbasierte Auswahl des Zielreizes bei einer visuellen Suchaufgabe; 3. zeitliche Entwicklung der Detektiongenauigkeit bei der Objekt-Substitutionsmaskierung. Wir untersuchten diese Prozesse mit einer Kombination aus humaner Elektroenzephalografie (EEG), eye tracking und psychophysischen Verhaltensmessungen. Zuerst untersuchten wir, wie die neuronale Repräsentation eines Reizes von seiner zeitlichen Nähe zur Sakkade geprägt wird. Wir zeigten, dass direkt vor der Sakkade erscheinende Reize am meisten durch Aufmerksamkeit und Suppression geprägt sind. In Studie 2 wurde die Sichtbarkeit des Reizes mit der Objekt-Substitutionsmaskierung verringert, und wir analysierten das Verhältnis zwischen sakkadischen Reaktionszeiten und ihrer Genauigkeit. Dazu erfassten wir neuronale Marker der Aufmerksamkeitslenkung zum Zielreiz und eine subjektive Bewertung seiner Wahrnehmbarkeit. Wir stellten fest, dass schnelle Sakkaden der Maskierung entgingen und Genauigkeit sowie subjektive Wahrnehmbarkeit erhöhten. Dies zeigt, dass bereits in frühen Verarbeitungsstadien eine bewusste und korrekte Wahrnehmung des Reizes entstehen kann. Wir replizierten diesen Befund für manuelle Antworten, um eine Verfälschung der Ergebnisse durch sakkadenspezifische Prozesse auszuschließen. Neben ihrer theoretischen Bedeutung liefern diese Studien einen methodischen Beitrag zum Forschungsgebiet der EEG-Augenbewegung: Entfernung sakkadischer Artefakte aus dem EEG bzw. Erstellung eines künstlichen Vergleichsdatensatzes. Die Arbeit stellt mehrere Ansätze zur Untersuchung der Dynamik visueller Wahrnehmung sowie Lösungen für zukünftige Studien dar.The visual system achieves a tremendous amount of processing as soon as we set eyes on a new object. Numerous processes are active already before eyes reach the object. This thesis explores the spatio-temporal properties of three such processes: attentional enhancement and saccadic suppression that accompany saccades to target; attentional selection of target in a visual search task; the timecourse of target detection accuracy under object-substitution masking. We monitored these events using a combination of human electrophysiology (EEG), eye tracking and behavioral psychophysics. We first studied how the neural representation of a visual stimulus is affected by its temporal proximity to saccade onset. We show that stimuli immediately preceding a saccade show strongest effects of attentional enhancement and saccadic suppression. Second, using object-substitution masking to reduce visibility, we analyzed the relationship between saccadic reaction times and response accuracy. We also collected subjective visibility ratings and observed neural markers of attentional selection, such as the negative, posterior-contralateral deflection at 200 ms (N2pc). We found that fast saccades escaped the effects of masking, resulted in higher response accuracy and higher awareness ratings. This indicates that early visual processing can trigger awareness and correct behavior. Finally, we replicated this finding with manual responses. Discovering a similar accuracy timecourse in a different modality ruled out saccade-specific mechanisms, such as saccadic suppression and retinal shift, as a potential confound. Next to their theoretical impact, all studies make a methodological contribution to EEG-eye movement research, such as removal of large-scale saccadic artifacts from EEG data and composition of matched surrogate data. In sum, this work uses multiple approaches to describe the dynamics of visual perisaccadic perception and offers solutions for future studies in this field.
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Trochimczyk, (geb Maria Anna Harley) Maja. "Music as Text, Musical Movement and Spatio-Temporal Features of the Musical Work". Bärenreiter Verlag, 1998. https://slub.qucosa.de/id/qucosa%3A37169.
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Zhou, Feng. "Spatial, Temporal and Spatio-Temporal Correspondence for Computer Vision Problems". Research Showcase @ CMU, 2014. http://repository.cmu.edu/dissertations/410.
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Many computer vision problems, such as object classification, motion estimation or shape registration rely on solving the correspondence problem. Existing algorithms to solve spatial or temporal correspondence problems are usually NP-hard, difficult to approximate, lack flexible models and mechanism for feature weighting. This proposal addresses the correspondence problem in computer vision, and proposes two new spatio-temporal correspondence problems and three algorithms to solve spatial, temporal and spatio-temporal matching between video and other sources. The main contributions of the thesis are: (1) Factorial graph matching (FGM). FGM extends existing work on graph matching (GM) by finding an exact factorization of the affinity matrix. Four are the benefits that follow from this factorization: (a) There is no need to compute the costly (in space and time) pairwise affinity matrix; (b) It provides a unified framework that reveals commonalities and differences between GM methods. Moreover, the factorization provides a clean connection with other matching algorithms such as iterative closest point; (c) The factorization allows the use of a path-following optimization algorithm, that leads to improved optimization strategies and matching performance; (d) Given the factorization, it becomes straight-forward to incorporate geometric transformations (rigid and non-rigid) to the GM problem. (2) Canonical time warping (CTW). CTW is a technique to temporally align multiple multi-dimensional and multi-modal time series. CTW extends DTW by incorporating a feature weighting layer to adapt different modalities, allowing a more flexible warping as combination of monotonic functions, and has linear complexity (unlike DTW that has quadratic). We applied CTW to align human motion captured with different sensors (e.g., audio, video, accelerometers). (3) Spatio-temporal matching (STM). Given a video and a 3D motion capture model, STM finds the correspondence between subsets of video trajectories and the motion capture model. STM is efficiently and robustly solved using linear programming. We illustrate the performance of STM on the problem of human detection in video, and show how STM achieves state-of-the-art performance.
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Bai, Ping Truong Young K. Smith Richard L. "Temporal-spatial modeling for fMRI data". Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2007. http://dc.lib.unc.edu/u?/etd,1481.
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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2007.Title from electronic title page (viewed Apr. 25, 2008). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Statistics and Operations Research." Discipline: Statistics and Operations Research; Department/School: Statistics and Operations Research.
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Bonsall, Michael B. "Temporal and spatial insect population dynamics". Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406839.
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Liddle, Elizabeth B. "Temporal and spatial attention in dyslexia". Thesis, University of Nottingham, 2006. http://eprints.nottingham.ac.uk/14422/.
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It was hypothesized that the deficits underlying reading impairment may arise from supra-modal deficits in temporal and spatial attention, disrupting, on the one hand, the ability to segment the temporally ordered phonemes of language and thus the acquisition of decoding skills, and, on the other, the ability to integrate spatially and temporally ordered orthographic information acquired from the fluent visual scanning of written text. Temporal and spatial attentional deficits in dyslexia were investigated using a lateralized visual temporal order judgment (TOJ) paradigm that allowed both sensitivity to temporal order and spatial attentional bias to be measured. Dyslexic and non-dyslexic participants were required to report the temporal order of two simple visual stimuli presented in either the same or different lateral hemifields. Findings indicated that dyslexic participants showed markedly impaired sensitivity to temporal order, and that the degree of impairment was correlated with the severity of their dyslexia. Furthermore, the findings suggested that at least three partially dissociated deficits may underlie both impaired TOJ task performance and reading disorder. One is a deficit associated with difficulty in reporting the temporal order of two visual stimuli, particularly when the first is presented in right hemifield; with slow word recognition and non-word reading; and with deficits in spelling and phonological skill. This constellation of deficits was interpreted as reflecting deficits in networks in left cerebral hemisphere implicated in phoneme-grapheme mapping and visual orienting. The second is a deficit that is associated with a rightward attentional bias; with inaccurate non-word reading that is worse than predicted by phonological skill or by word recognition; and with poor sustained attention. This constellation of impairments was interpreted as evidence of a deficit in right-lateralised networks implicated in the modulation of arousal, and possibly reflecting a “developmental left-neglect” syndrome. A third deficit was associated with impaired temporal order sensitivity, regardless of hemifield presentation; with symptoms of Attentional Deficit and Hyperactivity Disorder (ADHD); and with increased interference from distractor stimuli. This constellation of deficits suggests that the impaired network is implicated in executive control of attention, including conflict resolution and working memory. The results of the investigation as a whole suggests that the reading impairments of dyslexia may arise from attentional deficits that have with substantial overlap with those of ADHD, and include deficits in attentional networks implicated in orienting attention to temporally presented stimuli.
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Kan, Jing. "Spatial-temporal source reconstruction for magnetoencephalography". Thesis, University of York, 2011. http://etheses.whiterose.ac.uk/1636/.
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Magnetoencephalography (MEG) is a new non-invasive technique for the functional imaging of the human brain. It has been widely used in both research and clinical applications, for it has several superior properties, including a high-temporal resolution with no interference from the bone or the head-like fluid to the signal spatial transformation. In this thesis, we aim to develop a framework for MEG spatial-temporal current course reconstruction by introducing classical methods from the pattern recognition theory into medical imaging. These applications provide a new angle for research in MEG source reconstruction with the solution for source reconstruction at a single point, and improvements of the reconstruction on spatially and temporally. The whole thesis is based on three topics, which are designed to be parts of an integrated reconstruction process, and each of them are interrelated, rather than independent from each other. We firstly introduce the source reconstructionmethod at a single time point using the basis function extraction. In light of the assumption that the Laplacian eigenvectors of mesh can be the analogous to the basis functions that represent the cortex mesh; we build a new model to describe the current source that is distributed on each mesh vertex. This model consists of analogous basis functions and unknown weighted coefficients. In terms of experiment results, this algorithm shows good reconstructed property to the single stimulus, as well as the supercial stimulus on the cortical surface. Secondly, with respect to the spatial reconstructed sources by basis function method from the last topic, we build a new solution for improving the spatial-resolution of MEG source reconstruction at a single time point by introducing a classical method ( the Bayesian super-resolution method) from the pattern recognition theory. Although the approach is designed based on the reconstruction from basis functions, it is also feasible for other spatial reconstruction methods to improve the spatial-resolution. From the numerical experiment results, it is apparent that the spatial resolution has been effectively improved. Then, the MEG measurement system in the temporal field is assumed to be a linear dynamic system where the classical methods, Kalman filter and Kalman smoother, are applied as the solution for the estimation of source in time course. The Kalman filter is used to estimate the dynamic state while the Kalman smoother is applied for correcting the source distribution of the hidden state with the EMalgorithm. This approach shows superior performance to solve the inverse problem. It extends the improvement in source reconstruction using the temporal field. We construct the synthetic data as well as apply the realMEG data throughout all the experimental test of my work. In summary, this thesis builds three algorithms, which aim to reconstruct the MEG source distribution on spatial and temporal field respectively aided by methods from pattern recognition. This work provides a new angle of using the pattern recognition theory for MEG source reconstruction. Meanwhile, we also explore a new direction for applying the theory of pattern recognition. This work not only provides a good integration between these two fields, but also encourage future interactions.
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Wang, Qian. "Characterizing InternetWorm Spatial-Temporal Infection Structures". FIU Digital Commons, 2010. http://digitalcommons.fiu.edu/etd/294.
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Since the Morris worm was released in 1988, Internet worms continue to be one of top security threats. For example, the Conficker worm infected 9 to 15 million machines in early 2009 and shut down the service of some critical government and medical networks. Moreover, it constructed a massive peer-to-peer (P2P) botnet. Botnets are zombie networks controlled by attackers setting out coordinated attacks. In recent years, botnets have become the number one threat to the Internet. The objective of this research is to characterize spatial-temporal infection structures of Internet worms, and apply the observations to study P2P-based botnets formed by worm infection. First, we infer temporal characteristics of the Internet worm infection structure, i.e., the host infection time and the worm infection sequence, and thus pinpoint patient zero or initially infected hosts. Specifically, we apply statistical estimation techniques on Darknet observations. We show analytically and empirically that our proposed estimators can significantly improve the inference accuracy. Second, we reveal two key spatial characteristics of the Internet worm infection structure, i.e., the number of children and the generation of the underlying tree topology formed by worm infection. Specifically, we apply probabilistic modeling methods and a sequential growth model. We show analytically and empirically that the number of children has asymptotically a geometric distribution with parameter 0.5, and the generation follows closely a Poisson distribution. Finally, we evaluate bot detection strategies and effects of user defenses in P2P-based botnets formed by worm infection. Specifically, we apply the observations of the number of children and demonstrate analytically and empirically that targeted detection that focuses on the nodes with the largest number of children is an efficient way to expose bots. However, we also point out that future botnets may self-stop scanning to weaken targeted detection, without greatly slowing down the speed of worm infection. We then extend the worm spatial infection structure and show empirically that user defenses, e.g., patching or cleaning, can significantly mitigate the robustness and the effectiveness of P2P-based botnets. To counterattack, we evaluate a simple measure by future botnets that enhances topology robustness through worm re-infection.
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Kaphle, Manindra. "Simulations of human movements through temporal discretization and optimization". Licentiate thesis, KTH, Mechanics, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4585.
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Study of physical phenomena by means of mathematical models is common in various branches of engineering and science. In biomechanics, modelling often involves studying human motion by treating the body as a mechanical system made of interconnected rigid links. Robotics deals with similar cases as robots are often designed to imitate human behavior. Modelling human movements is a complicated task and, therefore, requires several simplifications and assumptions. Available computational resources often dictate the nature and the complexity of the models. In spite of all these factors, several meaningful results are still obtained from the simulations.
One common problem form encountered in real life is the movement between known initial and final states in a pre-specified time. This presents a problem of dynamic redundancy as several different trajectories are possible to achieve the target state. Movements are mathematically described by differential equations. So modelling a movement involves solving these differential equations, along with optimization to find a cost effective trajectory and forces or moments required for this purpose.
In this study, an algorithm developed in Matlab is used to study dynamics of several common human movements. The main underlying idea is based upon temporal finite element discretization, together with optimization. The algorithm can deal with mechanical formulations of varying degrees of complexity and allows precise definitions of initial and target states and constraints. Optimization is carried out using different cost functions related to both kinematic and kinetic variables.
Simulations show that generally different optimization criteria give different results. To arrive on a definite conclusion on which criterion is superior over others it is necessary to include more detailed features in the models and incorporate more advanced anatomical and physiological knowledge. Nevertheless, the algorithm and the simplified models present a platform that can be built upon to study more complex and reliable models.
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Kaphle, Manindra. "Simulations of human movements trough temporal descretization and optimization /". Stockholm : Department of Mechanics, Royal Institute of Technology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4585.
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Woodgate, Philip James. "Hand movements reveal the temporal characteristics of visual attention". Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/5867/.
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This thesis applied a choice reaching task (CRT) to different visual search settings to investigate the temporal characteristics of visual attention. The initiation latency (IL) and maximum deviation (MD) of the reach trajectory provided the greatest insight into early and ongoing competition for selection. We replicated priming of pop-out (PoP) effects on IL and MD before using the PoP paradigm to examine motor system involvement in generating movement-relevant predictions. Predictable repetition of the target colour recruited the motor cortex but only when the colour signalled the target of an overt movement. We also demonstrated that reaches are affected by global-to-local scene processing presenting a novel dissociation of IL and MD. IL reflected global configural biases (bottom-up), whilst MD reflected local positional biases (top-down). Finally, we examined the influence of irrelevant features (IFs) on target selection. Attentional capture by the IF affected the entire selection process when the target colour and IF presence were unpredictable. When the IF could coincide with multiple search items performance was modulated by early proximity and late similarity grouping. Overall, the results demonstrate the ability of the CRT to investigate the time course of attentional processing above and beyond that provided by key-press response tasks.
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Naylor, Susan J. "Spatial context effects on temporal and spatial factors in map memory /". Thesis, Connect to Dissertations & Theses @ Tufts University, 1999.
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Thesis (Ph.D.)--Tufts University, 1999.Adviser: Holly A. Taylor. Submitted to the Dept. of Psychology. Includes bibliographical references (leaves 59-61). Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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Farr, Daniel. "Resolving the Temporal-Spatial Ambiguity With the Auroral Spatial Structures Probe". DigitalCommons@USU, 2014. https://digitalcommons.usu.edu/etd/3728.
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The behavior of the electric and magnetic fields in the upper atmosphere of the Earth is scientifically interesting but difficult to study, since balloons and aircraft are unable to fly high enough to measure it directly. Sounding rockets, which make a one-time flight carrying instruments that measure the environment around them, have been successfully used to study the upper atmosphere. As the rocket flies through the upper atmosphere, it radios down data about the environment. When scientists on the ground use this data to construct a picture of the upper atmosphere, they run into a problem: the fields reported by the rocket change over time, but it is not clear whether this is because these fields are actually changing in time, or just because the rocket has moved to a different place where the fields are different. This inability to determine whether changes are happening in time or space is called the temporal-spatial ambiguity.
This thesis describes the Auroral Spatial Structures Probe (ASSP), a sounding rocket mission that attempts to resolve the temporal-spatial ambiguity by using multiple payloads flying in formation. Several payloads will pass through and measure the same point in space one after another, which will enable us to see how the fields are changing over time.
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Weger, Ulrich Wolfgang. "Spatial and linguistic control of eye movements during reading". Diss., Online access via UMI:, 2005.
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Smith, Daniel T. "Does covert spatial attention depend on planned eye-movements?" Thesis, University of Nottingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416734.
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O'Dwyer, Rebecca. "Quantitative Analysis of Ictal Head Movements in Temporal Lobe Epilepsy". Diss., lmu, 2007. http://nbn-resolving.de/urn:nbn:de:bvb:19-82320.
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Greenlee, Jordan. "Temporal and spatial modeling of analog memristors". Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41215.
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As silicon meets its performance limits, new materials and methods for advancing computing and electronics as a whole are being intensely researched, as described in Chapter 1. Memristors are a fusion of these two research areas, with new materials being pursued concurrently to development of novel architectures to take advantage of these new devices. A background of memristors and an overview of different memristive developments in the field are reviewed in Chapter 2.
Chapter 3 delves into the physical mechanisms of analog memristors. To investigate and understand the operation of analog memristors, a finite element method model has been developed.
More specifically, the devices simulated include a simple memristor simulation where the lithium ions (dopants) are confined to the device, but allowed to move in response to a voltage applied across the device. To model a more physical memristor, charge carrier mobility dependence on dopant levels was added to the device, resulting in a simulated device that operates similarly to the first simulation. Thereafter, the effect of varying geometries was modeled, and it was determined that both the speed and the resistance change of the device were improved by increasing the ratio of the top and bottom metal contact lengths in a restrictive flow geometry. Finally, the effect of dopant removal was investigated. It was determined that if the greatest change in resistance is required, then the removal of dopants is the optimal operating regime for an analog memristor.
Through a greater understanding of analog memristors developed by the simulation described herein, researchers will be able to better harness their power and implement them in bio-inspired systems and architectures.
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Geberl, Cornelia. "Spatial and temporal resolution of bat sonar". Diss., Ludwig-Maximilians-Universität München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-160582.
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Osnas, Erik E. "Temporal and spatial structure of waterfowl communities". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ30815.pdf.
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Chorley, N. "Spatial and temporal analysis of sunspot oscillations". Thesis, University of Warwick, 2011. http://wrap.warwick.ac.uk/47200/.
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Sunspots are the most conspicuous feature seen on the solar photosphere and are manifestations of the solar magnetic field. Their study, then, may provide us with a greater understanding of the dynamo mechanism thought to be responsible for the generation of this field. In this thesis, the oscillations of sunspots are studied by making use of observational data from two instruments: the Nobeyama Radioheliograph (NoRH) and the Solar Optical Telescope (SOT) on board the Hinode spacecraft. First, a study of long period oscillations was undertaken in which two long period peaks (P > 10 min) were identified in the power spectra of time series generated from sets of images of 3 sunspots observed with NoRH. In addition, by using the techniques of period, power, correlation and lag mapping, it was found that the power in each of these peaks was concentrated over the umbral regions and that there were two regions of approximately equal size oscillating in anti-phase with each other. It was suggested that these properties could be signatures of a "shallow" sunspot. A follow-up study was then performed, in which the lifetimes of the long period oscillations were investigated over a period of 9 days. These oscillations were seen to dominate the spectra during this interval and the periods and amplitudes were stable during that time. A simple model of a damped, driven simple harmonic oscillator (in which the driving term was nonlinear) was proposed to explain the generation and support of the oscillations. Finally, a study of the spatial properties of the 3 minute oscillations was performed by applying the mapping techniques mentioned above to Hinode/SOT data. The distributions of power and lag of maximum correlation coefficient were found to be non-uniform over the sunspots under study and this may be indicative of inhomogeneities of the physical quantities in the structures.
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Richardson, Thomas Owen. "Spatial and temporal organisation within ant societies". Thesis, University of the West of England, Bristol, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.557142.
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In this thesis the organisation of colonies of the ant, Temnothorax albipennis, is investigated with a special focus on their spatial and temporal statistics. Individual-based modelling combined with analyses of experimental data are used extensively to infer the mechanisms that govern individual and collective behaviour. The unequal allocation of labour amongst different individuals, as manifested in skewed distributions of activity, is ubiquitous within the social insects. Early non-spatial individual-based models demonstrated that such skewed divisions of labour can self- organise through the interaction of fluctuating levels of stimuli associated with a task, with differentially sensitive agents that perform work upon the stimulus. Here, that modelling framework is extended by explicitly including space. This modification induces a 'percolation' effect, in which small differences amongst agents in their response thresholds, are related to large differences in their probabilities of performing work. The extension of the original fixed-threshold models of Division of Labour to include space means that they can be treated as a special case of diffusion in disordered media - a well studied branch of statistical mechanics. Staying at home to care for young or leaving to find food is one of the most fundamental divisions of labour. Here the rate of departures from ant nests and the collective activity of the individuals within the nest, are experimentally quantified. Both the rate of nest-leaving, and the inside-nest activity showed a non-linear decline over time. This and other results indicates that fluctuating record signals and repulsive ant-ant interactions play a significant role in colony organisation. A record signal is a new 'high water mark' in the history of a system. The dynamics of several complex but purely physical systems are also based on record signals but this is the first time they have been experimentally shown in a biological system. Finally, the generation of spatial pattern formation is experimentally investigated In the context of resilience to perturbations. The brood within the ant colony is often sorted into an intricate annular pattern, according to the developmental stage of the various rood types. Even after the pattern is completely destroyed, the workers are able to re-establish the pattern. The dynamics of this process of re-emergence is quantified in detail. Lastly, the possible utility of the pattern as a spatial cue to the workers is discussed.
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Crema, E. R. "Spatial and temporal models of Jomon settlement". Thesis, University College London (University of London), 2013. http://discovery.ucl.ac.uk/1382589/.
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The Jomon culture is a tradition of complex hunter-gatherers which rose in the Japanese archipelago at the end of the Pleistocene (ca. 13,000 cal BP) and lasted until the 3rd millennium cal BP. Recent studies increasingly suggest how this long cultural persistence was characterised by repeated episodes of change in settlement pattern, primarily manifested as cyclical transitions between nucleated and dispersed distributions. Although it has been suggested that these events correlate with population dynamics, shifts in subsistence strategies, and environmental change, to date there have been very few attempts to provide a quantitative analysis of spatio-temporal change in Jomon settlement and its possible causes. This thesis is an attempt to fill that lacuna by adopting a twin-track approach to the problem. First, two case studies from central Japan have been examined using a novel set of methods, which have been specifically designed to handle the intrinsic chronological uncertainty which characterises most prehistoric data. This facilitated the application of a probabilistic framework for quantitatively assessing the available information, making it possible to identify alternating phases of nucleated and dispersed pattern during a chronological interval between 7000 and 3300 cal BP. Second, computer simulation (by means of an agent-based model) has been used to carry out a formal inquiry into the possible underlying processes that might have triggered the observed changes in the settlement pattern. The aim of this simulation exercise was two-fold. First, it has been used as a theory-building tool, combining several models from behavioural ecology and cultural transmission theory in order to provide explicit expectations in relation to the presence and absence of environmental disturbances. Second, the outcome of the simulation has been used as a template for linking the observed patterns to possible underlying socio-ecological processes suggested by the agent-based model. This endeavour has shown how some of the largest changes in the empirically observed settlement patterns can be simulated as emerging from the internal dynamics of the system rather than necessarily being induced by external changes in the environment.
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White, Andrew. "Temporal and spatial dynamics of ecological systems". Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338459.
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Alqarni, M. S. "Spatial temporal distribution of helical gyrotactic swimmers". Thesis, University of Liverpool, 2018. http://livrepository.liverpool.ac.uk/3024800/.
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We consider a spherical swimmer that undergoes helical motion due to the existence of a propulsive torque which is not parallel to a propulsive force that pulls the cell through the fluid. In addition, the cell is bottom-heavy; the centre of gravity is offset from the centre of buoyancy which generates a gravitational torque. In the presence of shear, fluid viscosity generates a further torque. Because cells swim at low Reynolds number, these torques are balanced. This thesis extends the model developed in Bearon (2013) in two distinct directions. Firstly, we consider an extension to the case of a flow where the shear varies with position. We consider a downward flow in a vertical channel. We observe that depending on the parameters, cells may exhibit the classical accumulation towards the centre of the channel or display a new focussing away from the centre. Secondly, we develop the model to describe randomness associated with changes in cell orientation. This is done by developing a Fokker-Planck equation for helical swimmers in terms of Euler angles. The classical Fokker-Planck equation obtained by Pedley and Kessler (1992) is a special case of the equation derived in this thesis. To implement this model numerically as an individual based model, we derive the corresponding stochastic differential equations. The Fokker-Planck equation and stochastic differential equation are extended to examine the spatial-temporal distribution of helical swimmers. We explore in detail how the horizontal distribution of cells in channel flow evolves to an equilibrium state, and how the evolution depends on the model parameters. For non-helical swimmers, we compare the result of the model to the recent experiments of Croze et al (2017).
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Walford, Hannah Louise. "Spatial and temporal variation of African epeirogeny". Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620082.
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