Grounded in Bronfenbrenner's (1979) Ecological Systems Theory and through the application of cross-classified random effects models, the goal of this study was to examine simultaneously neighborhood and school influences on adolescent academic achievement and risk of obesity, as well as the moderating effects of schools on these outcomes. By examining concurrently neighborhood and school influences on achievement and risk of obesity, this study aimed to fill gaps in the social determinants literature. For example, it is unclear if where an adolescent lives or where she/he attends school has a stronger influence on academic achievement. We also do not know if schools can moderate neighborhood influences on adolescent achievement, nor do we know much about the relationships among schools, neighborhoods, and adolescent risk for obesity. Using data from the National Longitudinal Study of Adolescent Health and the Adolescent Health and Academic Achievement study, four research questions were investigated: (1) To what extent are neighborhood influences on U.S. middle and high school students' academic achievement moderated by school environments? (2) What are the relative influences of neighborhood and school environments on U.S. middle and high school students' academic achievement? (3) To what extent are neighborhood influences on U.S. middle and high school students' risk of obesity moderated by school environments? (4) What are the relative influences of neighborhood and school environments on U.S. middle and high school students' risk of obesity? Findings did not suggest a moderating relationship between neighborhood and school factors examined in this study. In terms of relative relationships with academic achievement, three neighborhood factors (affluence, racial composition, and urbanicity) and two school characteristics (student body racial composition and school socioeconomic status) appeared to have the strongest relationships with adolescent achievement after controlling for individual and other neighborhood and school characteristics. For adolescent risk of obesity, neighborhood affluence and racial composition had statistically significant unique associations, whereas no school factors evidenced statistically significantly relationships with risk of obesity after controlling for other factors. Results of the study were interpreted in terms of contributions to the social determinants literature, as well as recommendations for the improvement of future large-scale surveys.

Le concept de stress s’est imposé comme un objet de la pensée scientifique, qui connaît depuis de nombreuses années un grand succès de vulgarisation auprès du grand public, devenant ainsi un objet de la pensée du sens commun. C’est cet objet dans le cadre du travail, que nous avons étudier dans une recherche exploratoire, à l’aide d’un questionnaire que nous avons élaboré, dans une approche psychosociale et des représentations sociales, dont le but est d’explorer l’existence de représentations sociales du stress au travail dans l’entreprise, de ses variations en fonction du sexe, à la fois dans et par la dynamique des relations hiérarchiques qui structurent l’entreprise (comparaison ascendante et horizontale) dans un contexte normal et de substitution, également d’explorer l’existence de valeurs sociales du stress au travail ainsi que des pratiques considérées comme pouvant être les plus efficaces pour faire face au stress au travail, et également des effets psychologiques en fonction des dimensions au MBI. Les résultats que nous présentons ici laisseraient apparaître l’existence d’un champ organisé de représentations du stress au travail et également de l’existence de rapports symboliques entre les statuts hiérarchiques et entre hommes et femmes. / The concept of stress has become an object of scientific thought, which for many years has been a popular success with the general public. So stress has become an object of common sense thinking. It is this object within the framework of the work, that we have studied in an exploratory research using a questionnaire that we have elaborated, in a psychosocial approach and Social Representations which purpose is to explore the existence of Social Representations of workplace stress in the workplace, of its variations according to sex, both in and part of the dynamics of the hierarchical relations that structure the company (upward and horizontal comparison) in a normal and substitution context, also to explore the existence of social values of work stress as well as practices considered to be most effective in coping with work-related stress, and also psychological effects according to MBI dimensions. The results we present here would reveal the existence of an organized field of representations of stress at work and also the existence of symbolic relationships between hierarchical statuses and between men and women.

Modeling patterns in temporal data has arisen as an important problem in engineering and science. This has led to the popularity of several dynamic models, in particular the renowned hidden Markov model (HMM) [Rabiner, 1989]. Despite its widespread success in many cases, the standard HMM often fails to model more complex data whose elements are correlated hierarchically or over a long period. Such problems are, however, frequently encountered in practice. Existing efforts to overcome this weakness often address either one of these two aspects separately, mainly due to computational intractability. Motivated by this modeling challenge in many real world problems, in particular, for video surveillance and segmentation, this thesis aims to develop tractable probabilistic models that can jointly model duration and hierarchical information in a unified framework. We believe that jointly exploiting statistical strength from both properties will lead to more accurate and robust models for the needed task. To tackle the modeling aspect, we base our work on an intersection between dynamic graphical models and statistics of lifetime modeling. Realizing that the key bottleneck found in the existing works lies in the choice of the distribution for a state, we have successfully integrated the discrete Coxian distribution [Cox, 1955], a special class of phase-type distributions, into the HMM to form a novel and powerful stochastic model termed as the Coxian Hidden Semi-Markov Model (CxHSMM). We show that this model can still be expressed as a dynamic Bayesian network, and inference and learning can be derived analytically. / Most importantly, it has four superior features over existing semi-Markov modelling: the parameter space is compact, computation is fast (almost the same as the HMM), close-formed estimation can be derived, and the Coxian is flexible enough to approximate a large class of distributions. Next, we exploit hierarchical decomposition in the data by borrowing analogy from the hierarchical hidden Markov model in [Fine et al., 1998, Bui et al., 2004] and introduce a new type of shallow structured graphical model that combines both duration and hierarchical modelling into a unified framework, termed the Coxian Switching Hidden Semi-Markov Models (CxSHSMM). The top layer is a Markov sequence of switching variables, while the bottom layer is a sequence of concatenated CxHSMMs whose parameters are determined by the switching variable at the top. Again, we provide a thorough analysis along with inference and learning machinery. We also show that semi-Markov models with arbitrary depth structure can easily be developed. In all cases we further address two practical issues: missing observations to unstable tracking and the use of partially labelled data to improve training accuracy. Motivated by real-world problems, our application contribution is a framework to recognize complex activities of daily livings (ADLs) and detect anomalies to provide better intelligent caring services for the elderly. / Coarser activities with self duration distributions are represented using the CxHSMM. Complex activities are made of a sequence of coarser activities and represented at the top level in the CxSHSMM. Intensive experiments are conducted to evaluate our solutions against existing methods. In many cases, the superiority of the joint modeling and the Coxian parameterization over traditional methods is confirmed. The robustness of our proposed models is further demonstrated in a series of more challenging experiments, in which the tracking is often lost and activities considerably overlap. Our final contribution is an application of the switching Coxian model to segment education-oriented videos into coherent topical units. Our results again demonstrate such segmentation processes can benefit greatly from the joint modeling of duration and hierarchy.

This thesis presents novel methods for creating and improving hierarchical hidden Markov models. The work centers around transforming a traditional tree structured hierarchical hidden Markov model (HHMM) into an equivalent model that reuses repeated sub-trees. This process temporarily breaks the tree structure constraint in order to leverage the benefits of combining repeated sub-trees. These benefits include lowered cost of testing and an increased accuracy of the final model-thus providing the model with greater performance. The result is called a merged and simplified hierarchical hidden Markov model (MSHHMM). The thesis goes on to detail four techniques for improving the performance of MSHHMMs when applied to information extraction tasks, in terms of accuracy and computational cost. Briefly, these techniques are: a new formula for calculating the approximate probability of previously unseen events; pattern generalisation to transform observations, thus increasing testing speed and prediction accuracy; restructuring states to focus on state transitions; and an automated flattening technique for reducing the complexity of HHMMs. The basic model and four improvements are evaluated by applying them to the well-known information extraction tasks of Reference Tagging and Text Chunking. In both tasks, MSHHMMs show consistently good performance across varying sizes of training data. In the case of Reference Tagging, the accuracy of the MSHHMM is comparable to other methods. However, when the volume of training data is limited, MSHHMMs maintain high accuracy whereas other methods show a significant decrease. These accuracy gains were achieved without any significant increase in processing time. For the Text Chunking task the accuracy of the MSHHMM was again comparable to other methods. However, the other methods incurred much higher processing delays compared to the MSHHMM. The results of these practical experiments demonstrate the benefits of the new method-increased accuracy, lower computation costs, and better performance.

The modern day tourists do not want to deal with the hassle of using a large number of travel guides and paper maps while travelling. They would prefer to be able to access required information via their mobile phones or Personal Digital Assistants (PDAs). We realise that the delivered information may be originally available in numerous information formats. To support the administrator of the tourist guides the programme is required to help sorting information from these different sources and to help inserting them into a system. Our goal with this project is to develop a software support for processing information import via a graphical user interface, to support the administrator in identifying and extracting the appropriate sight information from various resources. The interface also helps in transferring and storing the structured and unstructured data into the TIP database.

This thesis develops a number of graph-based techniques that are capable of measuring the dynamic behaviour of a network and discusses their application in network management. By representing a computer network as a time series of uniquely labelled graphs, it is possible to measure the degree of change that has occurred between a pair of graphs, and hence the dynamics in a network. Concepts introduced include the median graph, intra- and inter- graph clustering, and hierarchical graph representations. The focus is on producing efficient algorithms and improved measures of network change. It is believed that these graph-based techniques for measuring network dynamics have great potential in network anomaly detection, and thus will improve reliability of enterprise intranets.

Rivers around the world are under increasing pressure from a variety of human activities. Effective management of riverine landscapes requires an ecosystem approach and one that recognises the complex interactions between their physical, chemical and biological components. Perceptions of pattern and process are central to our understanding of riverine landscapes. Pattern and process operate over multiple scales to produce heterogeneous mosaics of landscape patches that change over time. Hierarchical patch dynamics provides a useful approach to unravel pattern and process at multiple scales in riverine landscapes. This thesis adopts a hierarchical patch dynamics approach to investigate floodplain sediment and nutrient dynamics within the Barwon-Darling River in South Eastern Australia. The flow regime of the Barwon-Darling River is highly variable. As a result, it has a complex channel cross section featuring inset-floodplain surfaces that occur at multiple elevations within the channel trough. These surfaces formed the focus of this study. The texture of inset- floodplain surface sediments displays a patchy spatial distribution and one that did not reflect lateral or longitudinal gradients within this floodplain landscape. Rather a sediment textural patch mosaic was identified. Nutrient concentrations associated with the surface sediments of the inset-floodplains were also shown to vary significantly resulting in a nutrient patch mosaic. This spatial nutrient mosaic was enhanced by factors including the surface elevation of the floodplain surface. Sediment and nutrient exchange between the river channel and inset-floodplain surfaces was measured during several flows in 2001, 2002 and 2005. Pin and sediment trap data showed that significant quantities of sediment were exchanged between the river channel and floodplain surfaces during inundation with both cut and fill processes occurring. Patterns in sediment exchange appear to be related to local sediment supply and seasonal sediment exhaustion, rather than the top down geomorphic constraints considered. These material exchanges resulted in a change to the spatial configuration of the sediment textural patch mosaic. Distinct new sediment textural patches were created following inundation, while other patches were lost post inundation and other patches changed sediment textural character to move into pre-existing patches. Thus a truly dynamic sediment textural mosaic exists within this floodplain landscape. Nutrient concentrations associated with floodplain sediments also changed over time. While nutrient concentrations increased after the December 2001 flow event, they generally decreased after the March 2002 event, highlighting their dynamic nature over time. The spatial distribution of nutrient concentrations also varied over time, with a 40 percent change to the nutrient mosaic as a result of the March 2002 flow event. In addition to the influence of the changing physical template (sediment texture mosaic), nutrient concentrations were shown to be influenced by rainfall processes on non flooded surfaces, and also a number of top-down constraints and bottom-up influences operating over multiple spatial scales. Overall, the inset-floodplains studied in this thesis acted primarily as sediment and nutrient sinks, and were a source for dissolved nutrients. Nutrient exchange was associated with the exchange of sediments in this riverine landscape, over both inter-flow and decadal timescales. It was demonstrated that water resource development within the catchment reduced the number, magnitude and duration of flow events down the Barwon-Darling River and as a result reductions in the exchange of sediment, associated and dissolved nutrients between inset-floodplains and the main river channel were calculated. The greatest reductions were with the release of dissolved nutrients (42-25 percent) and the exchange of sediment and associated nutrients from high level surfaces (43 percent). Effective conservation and management of riverine ecosystems must occur at the correct scale. This study identified potential nutrient hotspots at several scales in the Barwon-Darling floodplain landscape that could be targeted by management. The low predictability of the location of nutrient hotspots at the inset-floodplain scale over time means that environmental flows should be targeted at high level surfaces (<25 000 MLD-1) that provide long term sources of carbon to the river channel. Conserving flows of this magnitude will also reinstate flow variability, an important facet of the Barwon-Darling River?s hydrology that has been changed by water resource development. The research presented in this thesis highlights the importance of not only considering pattern and process at multiple scales, but also the way in which these processes influence landscape patterns over time, leading to the identification of the appropriate scales that can best be targeted for the conservation of these systems.

Career plateau has been identified as stressful experiences that can lead to employee negative feelings and attitudes in the workplace. However, empirical studies that examine how career plateau relates to employee outcomes and the conditions that moderate the above relationships have been scarce. Using an occupational stress model as the foundation, this study examined whether two types of career plateau (i.e., hierarchical plateau and job content plateau) relate to employee outcomes (emotional exhaustion, job satisfaction, and affective organizational commitment). Furthermore, this study examined whether the proposed psychological processes (future career uncertainty and subjective monotony) mediate the above relationships and whether components of workplace spirituality (i.e., inner life and belongingness to community) moderate the relationship between career plateau and psychological processes. Based on responses of 243 participants, hierarchical regression results indicate that both plateaus relate negatively with job satisfaction, job involvement, and affective organizational commitment. However, only hierarchical plateau relates positively to emotional exhaustion, whereas job content plateau is not related to emotional exhaustion. Also, individuals’ future career uncertainty partially mediates the relationship between hierarchical plateau and employee emotional exhaustion and job attitudes, whereas subjective monotony partially mediates the relationship between job content plateau and job attitudes, but completely mediates the relationship between job content plateau and emotional exhaustion. Furthermore, only the inner life component of workplace spirituality moderates the relationship between hierarchical plateau and future career uncertainty. Based on the study findings, managerial implications, limitations and suggestions for future research directions are given.

<p>Background: The description of different characters in soapoperas are often exaggerated to catch the viewers interest and to present an exiting content. The phenomenon that takes place in soapoperas can often relates to every-day- life-situations. The viewers should recognise them selves in the content, the imaginary situations and the characters should be normal but at the same time exaggerated and twisted to catch the viewers attention. This means that the characters in Rederiet should have connections to the real world and this makes it interesting to study how the different styels of leadership are descibed.</p><p>Purpose: The purpose is to analyse and compare three choosen characters in the soapopera Rederiet, from existing leadership thoeries. To identify leadership on three hierarchical levels – head of machinery, superintendent and captain – and to analyse how leadership are descibed in the soapopera. </p><p>Realization: The study is based on videotaped episodes of the soapopera Rederiet. </p><p>Conclusion: The mediate illustrations can be compared to the scientific theories. The three managers are different from eachother. Leadership depends on the managers acting, in the soapopera and in real life. The mediate illustrations shows that leadership are different and dependent on personality and hierarchical position. This holds for Rederiet and for real organizations.</p>

The recent development of DNA microarray technology is creating a wealth of gene expression data. Typically these datasets have high dimensionality and a lot of varieties. Analysis of DNA microarray expression data is a fast growing research area that interfaces various disciplines such as biology, biochemistry, computer science and statistics. It is concluded that clustering and classification techniques can be successfully employed to group genes based on the similarity of their expression patterns. In this paper, a hierarchical multi-bottleneck classification method is proposed, and it is applied to classify a publicly available gene microarray expression data of budding yeast Saccharomyces cerevisiae. / Singapore-MIT Alliance (SMA)