• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 188
  • 59
  • 40
  • 29
  • 9
  • 7
  • 4
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • Tagged with
  • 393
  • 393
  • 100
  • 68
  • 48
  • 43
  • 42
  • 37
  • 29
  • 29
  • 29
  • 29
  • 27
  • 27
  • 25
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Gait Analysis in Adolescents with Idiopathic Scoliosis: A Systematic Review

Bains, Mandeep Kaur January 2015 (has links)
Title Gait Analysis in Adolescents with Idiopathic Scoliosis: A Systematic Review. Aim The role of spine is vital as a gait stabilizer. Gait analysis may provide a more holistic view of how the body behaves to idiopathic scoliosis among adolescents. The aim of this thesis is to review the effectiveness and validity of gait analysis in examining AIS, and secondly to assess how the gait of AIS patients differ from adolescents without scoliosis. Method A systematic review of the topic was conducted. Information was gathered from six e-databases, and seventeen articles were selected, of which seven focusing solely on AIS subjects (i.e. non-comparative) and ten were focusing on AIS in relation to control subjects (i.e. comparative). Results Spatio-temporal (STP), kinematic, kinetic and EMG parameters show significant changes in AIS subjects during walking. But variations between results, lack of data for certain parameters and no significant relationship between gait parameters and scoliosis was also seen. Furthermore, AIS subjects differ in performance compared to non-scoliosis adolescents in at least one gait parameter across all studies. This includes abnormalities in muscle activity, less economical use of the body, poorer performance in kinematic parameters and differences in STP such as step...
62

Padrões espaciais de abundância e dinâmica populacional em longo prazo do camarão sete-barbas Xiphopenaeus kroyeri (Heller, 1862) na Enseada de Ubatuba, SP / Long-term pattern of spatial abundance and population dynamics of the seabob shrimp Xiphopenaeus kroyeri (Heller, 1862) in Ubatuba Bay, São Paulo State, Brazil

Heckler, Gisele Salgado 29 August 2014 (has links)
A análise de uma população em longo prazo permite a identificação da ausência ou presença de variações nos padrões de ciclo de vida, de distribuição espaço-temporal e dinâmica populacional. O ciclo de vida do camarão sete-barbas Xiphopenaeus kroyeri foi investigado na Enseada de Ubatuba, litoral norte do Estado de São Paulo (23º25\' - 23º27\'S / 45º00\' - 45º03\' W) ao longo de um intervalo de treze anos. Amostras de material biológico, de água de fundo e de sedimento foram coletadas em quatro pontos de amostragem em três períodos de 12 meses cada: janeiro a dezembro de 1998, julho de 2006 a junho de 2007 e setembro de 2010 a agosto de 2011. Dados obtidos em 1999 foram incluídos para as análises de crescimento individual, de longevidade e de idade de maturação. Altas abundâncias de fêmeas maduras e de jovens foram respectivamente associadas a valores de temperatura da água de fundo acima e abaixo da média da região. Indivíduos adultos predominaram em pontos com variação temporal da composição granulométrica do sedimento enquanto que os jovens se estabeleceram naqueles em que o sedimento permaneceu fino entre os períodos. Em 1998, a abundância de jovens, o peso individual de machos e fêmeas de todas as categorias demográficas, a idade de maturação morfológica e fisiológica e a longevidade foram maiores do que nos outros períodos. Os parâmetros da função de crescimento de machos e fêmeas variaram entre os períodos, sem apresentarem uma tendência temporal clara. Os padrões anuais de reprodução e recrutamento foram bastante semelhantes entre os períodos. As alterações nos fatores ambientais provocadas por variações na dinâmica de massas de água, pela ocorrência de El Niño e alterações na intensidade de pesca foram consideradas como possíveis agentes relacionadas às variações nos padrões do ciclo de vida da espécie na região / Long-term studies on a population provide detection of the presence or absence of interannual variation in patterns of its life cycle, spatio-temporal distribution, and dynamics. This study investigate the population of the seabob shrimp Xiphopenaeus kroyeri within a period of 13 years in Ubatuba Bay, northern coast of São Paulo state, Brazil (23º25\' - 23º27\'S / 45º00\' - 45º03\' W). Shrimp, bottom water and sediment samples were collected from four sampling sites during three 12-month periods: January-December 1998, July 2006-June 2007, and September 2010-August 2011. Monthly data collected in 1999 were included in growth, longevity and maturation age analyses. High abundance of mature females and juveniles were associated to the occurrence of temperature values below and above the region average, respectively. Adults predominated in sites that showed temporal variation of sediment texture while juveniles occurred in sites where sediment remained fine between the study periods. In the 1998 period values of juveniles were more abundant, individual weight of all demographic categories was higher, both morphological and physiological maturity was attained later and lifespan was longer than on the following periods. Growth function parameters of males and females varied between periods with no clear temporal trend. Monthly patterns of reproduction and recruitment were similar between the study periods. Changes in the environmental conditions caused by variations in the dynamics of the local water masses, occurrence of El Niño and fishery intensity were considered as possible factors related to the interannual variations in the life cycle pattern of X. kroyeri in the study region
63

Um estudo sobre a distribuição da raiva no Estado do Paraná de 1981 a 2012 / A study on the rabies distribution on Paraná State from 1981 to 2012

Sandri, Thaisa Lucas 17 March 2014 (has links)
A raiva é uma zoonose viral que afeta o Sistema Nervoso Central (SNC) causando encefalite e meningoencefalite, de evolução aguda e fatal, que acomete mamíferos carnívoros e morcegos, e periodicamente se manifesta sob a forma de epizootias ou surtos epidêmicos em populações humanas. Neste estudo foram analisadas 16.190 amostras de bovinos, equídeos e morcegos, e menos frequentemente de outros mamíferos durante o período de 1981 a 2012, provenientes do Estado do Paraná. Desse total, 2.766 amostras foram positivas para raiva; 81,74% foram de bovinos, 10,34% de equídeos, 4,05% de morcegos, 2,31% em animais de produção não bovinos, 1,52% em caninos e 0,04%em outros animais. Ao longo da série histórica, há, para os bovinos, uma tendência de aumento das notificações e não foram observadas variação sazonal e cíclica. Na análise espaço-temporal foi detectado um aglomerado mais provável de notificações de raiva em bovinos, envolvendo 20 municípios da região litorânea e metropolitana de Curitiba entre 1981 e 1987. Além dele, foram detectados seis aglomerados secundários sugerindo uma migração da raiva ao longo do tempo no Estado do Paraná. Ao longo da série histórica dos equídeos há uma tendência de diminuição das notificações e não foram observadas variação sazonal e cíclica. Os clusters encontrados na análise espaço-temporal da raiva nos equídeos corroboram com aqueles encontrados na análise dos bovinos localizados nas mesmas regiões durante no mesmo período, sugerindo a migração do vírus da raiva no mesmo sentido da observada na análise dos bovinos. Durante o período de 1981 a 1997, os casos de raiva em morcegos acompanham o trajeto da migração dos aglomerados dos bovinos e dos equídeos, o que demonstra que a raiva ocorre endemicamente no território do Estado do Paraná em herbívoros e morcegos. / Rabies is a viral zoonosis that affects the central nervous system (CNS) causing encephalitis and meningoencephalitis, acute and fatal outcome, which affects mammalian carnivores and bats, and periodically manifests itself in the form of epidemics or outbreaks in human populations. In this study 16,190 samples of cattle, horses and bats, and less frequently other mammals were analyzed during the period 1981 to 2012, from the State of Paraná. Of this total, 2,766 samples were positive for rabies; 81.74 % were bovine, equine 10.34 %, 4.05 % of bats, 2.31 % in livestock no bovine, 1.52 % in canine, and 0.04% in other animals. Throughout the time series, there is, for cattle, a trend of increased reporting and no seasonal or cyclical variations were observed. In spatio-temporal analysis, more likely to notifications of rabies in cattle, a cluster involving 20 municipalities in coastal and metropolitan Curitiba between 1981 and 1987 was detected. Besides this, six sub clusters were detected suggesting a migration of anger over time in the state of Paraná. Throughout the historical series of equine there is a downward trend in notifications and no seasonal and cyclical variations were observed. Clusters found in the spatio-temporal analysis of rabies in horses corroborate those found in the analysis of cattle located in the same regions during the same period, suggesting the migration of rabies virus in the same direction as that observed in the cattle analysis. During the period from 1981 to 1997, cases of rabies in bats follow the migration path of clusters of bovine and equine. This shows that rabies is endemic in the state of Paraná in herbivores and bats.
64

Spatio-temporal representation and analysis of facial expressions with varying intensities

Sariyanidi, Evangelos January 2017 (has links)
Facial expressions convey a wealth of information about our feelings, personality and mental state. In this thesis we seek efficient ways of representing and analysing facial expressions of varying intensities. Firstly, we analyse state-of-the-art systems by decomposing them into their fundamental components, in an effort to understand what are the useful practices common to successful systems. Secondly, we address the problem of sequence registration, which emerged as an open issue in our analysis. The encoding of the (non-rigid) motions generated by facial expressions is facilitated when the rigid motions caused by irrelevant factors, such as camera movement, are eliminated. We propose a sequence registration framework that is based on pre-trained regressors of Gabor motion energy. Comprehensive experiments show that the proposed method achieves very high registration accuracy even under difficult illumination variations. Finally, we propose an unsupervised representation learning framework for encoding the spatio-temporal evolution of facial expressions. The proposed framework is inspired by the Facial Action Coding System (FACS), which predates computer-based analysis. FACS encodes an expression in terms of localised facial movements and assigns an intensity score for each movement. The framework we propose mimics those two properties of FACS. Specifically, we propose to learn from data a linear transformation that approximates the facial expression variation in a sequence as a weighted sum of localised basis functions, where the weight of each basis function relates to movement intensity. We show that the proposed framework provides a plausible description of facial expressions, and leads to state-of-the-art performance in recognising expressions across intensities; from fully blown expressions to micro-expressions.
65

Mapping and assessment of changes in ecosystem service delivery : a historical perspective on the Tweed catchment, Scotland, UK

Ncube, Sikhululekile January 2016 (has links)
For centuries, river catchments and their constituent habitats have been altered and modified through various human activities to maximise provision of tangible benefits like food and water, while impacting on their capacity to provide other less obvious but equally important benefits for human survival. However, in the last few decades, perceptions on the role of catchments as mere providers of tangible benefits have been changing, as recognition has been given to other human beneficial services like regulation of floods. This recognition has drawn increased interest in both science and policy, towards understanding human-nature relations and how approaches like the ecosystem services concept can inform sustainable management of catchments. Although, the multiple and differently weighted relationships existing between habitats and ecosystem services have been acknowledged, the relationship between spatio-temporal change in habitats and spatio-temporal change in ecosystem services delivery, has not received as much attention in the research literature. In this thesis, it is argued that this is an important omission as spatio-temporal habitat change could have broader consequences for ecosystem services provided by a catchment. On this basis, this study maps and assesses the influence of habitat changes across space and time on ecosystem services delivery at a local catchment scale. Approaches to assessing ecosystem service delivery across landscapes and catchments draw on habitat mapping data for those landscapes or catchments. Such data are in turn used as proxies for estimating different ecosystem services delivered by the landscape or catchment based on their integration with other spatial or non-spatial data. To date this approach has been applied to assess contemporary delivery of different ecosystem services. The basis of the approach taken in this study involved comparing a pre-existing contemporary ecosystem service assessment of two chosen sub catchments of the Tweed catchment in Scotland, with a similar assessment based on a set of older “historic” habitat maps for the mid-20th century period. Derivation of the digital map base for the latter was a major focus of the present study. Aerial photography taken during the Royal Air Force surveys in the 1940s archived in the Royal Commission on Ancient and Historical Monuments of Scotland were obtained and first scanned digitally, arranged into a mosaic of adjacent images and ortho-rectified to remove camera distortion. These photo mosaics were then visually interpreted and, aided with ancillary data, the current (2009) habitat maps were edited and backdated to derive the historic habitat maps for the study catchments. The Spatial Evidence for Natural Capital Evaluation (SENCE) ecosystem services mapping approach was then used to translate generated habitat maps into ecosystem service supply maps. Findings show that the study catchments changed from multifunctional to intensively managed landscapes by 2009, with a higher capacity for supplying provisioning ecosystem services, while their capacity to supply regulating and supporting ecosystem services was reduced. Findings also show that a change in one habitat type results in changes in multiple ecosystem services, while changes in the spatial configuration of habitats reduces areas with high supply capacity for regulating and supporting ecosystem services. This study concludes that ecosystem service delivery is not only affected by changes in gross area of constituent habitats but also by spatial changes in the configuration and distribution of these habitats. In this regard, it is argued that recognising and understanding changes in ecosystem services adds an important strand in catchment management. It is therefore suggested that planning for future ecosystem services in catchment management needs to be informed by historic baselines.
66

Structured modeling & simulation of articular cartilage lesion formation : development & validation

Wang, Xiayi 01 July 2015 (has links)
Traumatic injuries lead to articular cartilage lesion formation and result in the development of osteoarthritis. Recent research suggests that the early stage of mechanical injuries involve cell death (apoptosis and necrosis) and inflammation. In this thesis, we focus on building mathematical models to investigate the biological mechanism involving chondrocyte death and inflammatory responses in the process of cartilage degeneration. Chapter 1 describes the structure of articular cartilage, the process of carti- lage degeneration, and reviews of existing mathematical models. Chapter 2 presents a delay-diffusion-reaction model of cartilage lesion formation under cyclic loading. Computational methods were used to simulate the impact of varying loading stresses and erythropoietin levels. The model is parameterized with experimental results, and is therefore clinically relevant. Due to numerical limitations using delay differential equations, a new model is presented using tools for population dynamics. Chapter 3 presents an age and space-structured model of articular cartilage lesion formation un- der a single blunt impact. Age structure is introduced to represent the time delay in cytokine synthesis and cell transition. Numerical simulations produce similar tempo- ral and spatial patterns to our experimental data. In chapter 4, we extend our model under the cyclic loading setting. Chapter 5 builds a spatio-temporal model adapted from the former models, and investigates the distribution of model parameters using experimental data and statistical methods. Chapter 6 concludes.
67

Spatially Indexed Functional Data

Gromenko, Oleksandr 01 May 2013 (has links)
The increased concentration of greenhouse gases is associated with the global warming in the lower troposphere. For over twenty years, the space physics community has studied a hypothesis of global cooling in the thermosphere, attributable to greenhouse gases. While the global temperature increase in the lower troposphere has been relatively well established, the existence of global changes in the thermosphere is still under investigation. A central difficulty in reaching definite conclusions is the absence of data with sufficiently long temporal and sufficiently broad spatial coverage. Time series of data that cover several decades exist only in a few separated regions. The space physics community has struggled to combine the information contained in these data, and often contradictory conclusions have been reported based on the analyses relying on one or a few locations. To detect global changes in the ionosphere, we present a novel statistical methodology that uses all data, even those with incomplete temporal coverage. It is based on a new functional regression approach that can handle unevenly spaced, partially observed curves. While this research makes a solid contribution to the space physics community, our statistical methodology is very flexible and can be useful in other applied problems.
68

Statistical Analysis and Modeling of PM<sub>2.5</sub> Speciation Metals and Their Mixtures

Ibrahimou, Boubakari 10 November 2014 (has links)
Exposure to fine particulate matter (PM2.5) in the ambient air is associated with various health effects. There is increasing evidence which implicates the central role played by specific chemical components such as heavy metals of PM2.5. Given the fact that humans are exposed to complex mixtures of environmental pollutants such as PM2.5, research efforts are intensifying to study the mixtures composition and the emission sources of ambient PM, and the exposure-related health effects. Factor analysis as well source apportionment models are statistical tools potentially useful for characterizing mixtures in PM2.5. However, classic factor analysis is designed to analyze samples of independent data. To handle (spatio-)temporally correlated PM2.5 data, a Bayesian approach is developed and using source apportionment, a latent factor is converted to a mixture by utilizing loadings to compute mixture coefficients. Additionally there have been intensified efforts in studying the metal composition and variation in ambient PM as well as its association with health outcomes. We use non parametric smoothing methods to study the spatio-temporal patterns and variation of common PM metals and their mixtures. Lastly the risk of low birth weight following exposure to metal mixtures during pregnancy is being investigated.
69

Spatio-Temporal Pre-Processing Methods for Region-of-Interest Video Coding

Karlsson, Linda S. January 2007 (has links)
<p>In video transmission at low bit rates the challenge is to compress the video with a minimal reduction of the percieved quality. The compression can be adapted to knowledge of which regions in the video sequence are of most interest to the viewer. Region of interest (ROI) video coding uses this information to control the allocation of bits to the background and the ROI. The aim is to increase the quality in the ROI at the expense of the quality in the background. In order for this to occur the typical content of an ROI for a particular application is firstly determined and the actual detection is performed based on this information. The allocation of bits can then be controlled based on the result of the detection.</p><p>In this licenciate thesis existing methods to control bit allocation in ROI video coding are investigated. In particular pre-processing methods that are applied independently of the codec or standard. This makes it possible to apply the method directly to the video sequence without modifications to the codec. Three filters are proposed in this thesis based on previous approaches. The spatial filter that only modifies the background within a single frame and the temporal filter that uses information from the previous frame. These two filters are also combined into a spatio-temporal filter. The abilities of these filters to reduce the number of bits necessary to encode the background and to successfully re-allocate these to the ROI are investigated. In addition the computational compexities of the algorithms are analysed.</p><p>The theoretical analysis is verified by quantitative tests. These include measuring the quality using both the PSNR of the ROI and the border of the background, as well as subjective tests with human test subjects and an analysis of motion vector statistics.</p><p>The qualitative analysis shows that the spatio-temporal filter has a better coding efficiency than the other filters and it successfully re-allocates the bits from the foreground to the background. The spatio-temporal filter gives an improvement in average PSNR in the ROI of more than 1.32 dB or a reduction in bitrate of 31 % compared to the encoding of the original sequence. This result is similar to or slightly better than the spatial filter. However, the spatio-temporal filter has a better performance, since its computational complexity is lower than that of the spatial filter.</p>
70

Application of Gis in Temporal and Spatial Analyses of Dengue Fever Outbreak : Case of Rio de Janeiro, Brazil

Achu, Denis January 2009 (has links)
<p>Since Dengue fever (DF) and its related forms, Dengue Hemorrhagic fever (DHF) and Dengue Shock Syndrome (DSS) have become important health concerns worldwide, it is also imperative to develop methods which will help in the analysis of the incidences. Dengue fever cases are growing in number as it also invades widely, affecting larger number of countries and crossing climatic boundaries. Considering that the disease as of now has neither an effective vaccine nor a cure, monitoring in order to prevent or control is the resorted alternative. GIS and its related technologies offer a wealth of interesting capabilities towards achieving this goal.</p><p><strong> </strong></p><p>The intention of this study was to develop methods to describe dengue fever outbreaks taking Rio de Janeiro, Brazil as a case study. Careful study of Census data with appropriate attributes was made to find out their potential influence on dengue fever incidence in the various regions or census districts. Dengue incidence data from year 2000 to year 2008 reported by the municipal secretariat of Rio was used to extract the necessary census districts. Base map files in MapInfo format were converted to shape files.  Using ArcGIS it was possible to merge the dengue fever incidence data with the available base map file of the City of Rio according to corresponding census districts. Choropleth maps were then created using different attributes from which patterns and trends could be used to describe the characteristic of the outbreak with respect to the socio-economic conditions. Incidence data were also plotted in Excel to see temporal variations. Cluster analysis were performed with the Moran I technique on critical periods and years of dengue outbreak. Using the square root of dengue incidence from January to April 2002 and 2008, inverse distance was selected as the conceptualised spatial relationship, Euclidean distance as the distance method. More detailed analyses were then done on the selected critical years of dengue outbreak, (years 2002 and 2008), to investigate the influence of socio-economic variables on dengue incidence per census district.</p><p> </p><p>Dengue incidence rate appeared to be higher during the rainy and warmer months between December and May. Outbreaks of dengue occurred in years 2002 and 2008 over the study period of year 2000 to 2008. Some factors included in the census data were influential in the dengue prevalence according to districts. Satisfactory results can be achieved by using this strategy as a quick method for assessing potential dengue attack, spread and possible enabling conditions. The method has the advantage where there is limited access to field work, less financial means for acquisition of data and other vital resources.</p><p>A number of difficulties were encountered during the study however and leaves areas where further work can be done for improvements. More variables would be required in order to make a complete and comprehensive description of influential conditions and factors.  There is still a gap in the analytical tools required for multi-dimensional investigations as the ones encountered in this study.  It is vital to integrate ‘GPS’ and ‘Remote Sensing’ in order to obtain a variety of up-to-date data with higher resolution.</p><p> </p>

Page generated in 0.1005 seconds