This thesis suggests a general approach for estimating the trend of a univariate time series. It begins by suggesting and defining a set of "desirable" trend properties, namely "Fidelity", "Smoothness", "Invariance" and "Additivity", which are then incorporated into the design of an appropriate non-stationary time series model. The unknown parameters of the model are then estimated using a wide selection of "optimal" procedures, each parameter having at least two such procedures applied to it. Attention is paid to the development of algorithms to implement the procedures in practice. The model is gradually extended from a basic, non-seasonal model consisting of a simple lagged trend to a general, seasonal model incorporating a variable parameter, general autoregressive trend.

The Ozark National Scenic Riverways (ONSR) has seen a wide range of recreationists since its establishment in 1964. To better understand these recreationists, Experience Use History (EUH) has been identified as a measure of exposure to ONSR. EUH is a construct used to identify how often a visitor frequents an area, as well as his or her history with that area. The purpose of this study is to identify the changes in river user demographics over the past 24 years and how these changes relate to EUH using time series analyses. Study field methods follow procedures of Rapid Assessment Visitor Inventory (RAVI), which has been periodically conducted at ONSR since 1972. This study utilizes questionnaires for which raw data were available, collected from 1986 through 2010 to conduct time series analyses of visitor demographics and EUH. EUH groupings were created using the methods of Smith et al. (2009), resulting in the identification of Casual Newcomers, Casual Veterans, Occasional, and Frequent visitors. While a wealth of information exists pertaining to EUH and general demographics, there is an absence of studies analyzing the dynamic relationship of these variables over time. This research examines for the first time if EUH classifications are also time-dependent or if they are functionally stable at a quarter-century time scale. EUH trends over time showed that Casual Newcomers have begun to transition into Casual Veterans throughout the riverways as their history and frequency of visits increased over the years. Changes in age, watercraft type, and gender were also detected resulting in an aging visitor group to ONSR, an increase in motorboat use, and a slow increase in the proportion of female visitors. Experiences, preferences, and attitudes were also analyzed in terms of both EUH and river district. Finally, average distance traveled by visitors was also analyzed showing ONSR to be a regional attraction attended by both urban and nonurban visitors. Overall this study suggests that visitor populations to ONSR are dynamic. Some of the most important findings of this study showed that EUH category for a given visitor can and does change over time. The Casual Newcomers and Casual Veterans had clear trends; all three river districts showed distinct trends of increasing Casual Veterans and decreasing Casual Newcomers over time but at varying rates of change in proportion. This finding coupled with the aging of visitors to ONSR, suggests that visitors are returning to the riverways and, over time, increasing in experience, thus transforming the Casual Newcomers into Casual Veterans.

In this text, submitted as my master’s thesis, I seek to examine the way that narrative in the comics medium is produced from a series of static illustrations and lexia using narratological methods that have either been previously discarded as having little to no value in the study of comics or that have been overlooked. The first chapter of the text, however, is most faithful to the established tradition of comics studies; in this first chapter, I argue that narrative is distributed visually within comics, essentially becoming part of the text’s visual field of representation. In the second chapter, I deploy Paul Ricoeur’s concept of mimesis to argue that the production of narrative is dependent on the interaction between distinct but related temporal levels. Through the interaction of these temporal levels, which, in comics, rely on the intervention of the visual space of the text, narrative is produced and reproduced by the active participation of the reader, who is responsible for creating connections between textual moments. Finally, in the third chapter, I seek to balance the subjectivity produced by the application of Ricoeur’s system to the comics medium by deploying Genette’s concepts of order, duration, and frequency in an effort to re-introduce some sense of determinateness and objectivity, suggesting that there are overarching patterns that comics narratives do tend to follow.

My aim in this thesis is to show how Plato differentiates the everlastingness of eternity from the everlastingness of time in the cosmogony of his Timaeus, where time is classified as the everlasting ‘moving image’ of ‘eternity-remaining-in-unity’ (Tim. 37c 6-d 7). Of course, as many scholars know, this distinction between eternity and time follows from his distinction between unchanging Being and ever-changing Becoming, so much so that our understanding of what it is that makes time the ‘image’ of eternity—and yet also something other than eternity—proves fundamental to our understanding of Platonic ontology. However, our understanding of Being and Becoming and the relation between them is complicated by the view that what exists in time was and is and will be, whereas what exists in eternity ‘is’ alone (Tim. 37e 4-38a 8). Does this mean that eternity is temporal, given that it ‘is’ in some sense? Or is eternity atemporal, given that it is itself distinguishable from time? Also, if eternity is atemporal, how should one conceive of atemporality in this particular respect? Does this entail existing altogether apart from time? Or can one speak of eternity as just another type of time, a timeless time, as it were? Not surprisingly, it has long been a matter of controversy among scholars whether the eternal ‘is’ is actually tensed or tenseless, temporal or timeless. So too, the very fact that eternity is said to be ‘remaining in unity’ has led some scholars to conceive of eternity as durational, and thus temporal in some sense, on the assumption that duration entails temporality. But then again, still other scholars speak of eternity as an ‘eternal present’ which is non-durational, precisely because it has its being ‘in unity’. By contrast, I argue that the Platonic distinction between Being and Becoming entails a twofold notion of everlastingness, the one temporal, the other extra-temporal, where the latter is signifying timelessness unqualifiedly. For I show that Plato conceives of time and temporal passage as the imperfectly everlasting image (aiônios eikôn) of eternity whilst understanding eternity to be perfectly everlasting (diaiônios), since eternal Being is subject to no passage from its essential being. Only in this way can one explain how the temporality of Becoming is akin to—yet also distinguishable from—the extra-temporality of Being, and then again why it is that both should be thought of as durational. Hence the scholarly assumption that duration entails temporality, an assumption commonly encountered in modern thought, is foreign to Plato. Nor again does it make sense to speak of an ‘eternal present’ apart from everlastingness, and thence apart from duration. So as to clarify this twofold notion of everlastingness it has proven necessary for my argument to touch upon another controversy surrounding the cosmogony of the Timaeus, namely, whether the universe, the realm of Becoming, has had a beginning at some time in the remote past (i.e., at the very first moment of time) or has had no single beginning, at least in a temporal sense (i.e., that it will have come into being ‘always’ (aei)). Scholars have given various arguments for both of these readings. However, I argue that one can resolve this issue by more closely analysing the possible meanings of the verb gegonen (viz. ‘It has come into being’), which is said of the universe as well as time (Tim. 28b 7, 38b 6). With respect to gegonen, the temporal ambiguity of its perfect aspect means that it might refer to a past event in the immediate past no less than in the remote past. Hence one can speak of the generation of time and the universe as everlasting, as a process of genesis having no single, distinct beginning at a time or even in time, but infinitely many beginnings, extending from the infinite past into the ever-emerging present. And that gegonen is ambiguous between past and present time is shown by the cosmological argument at Tim. 28b 2-c 2 and the status of god relative to creation. All in all, this reveals that time, being generate, is a feature of Becoming, not Being. It also reveals that time and the universe need not have had a beginning at some first moment of time.

Recreational screen time activities (e.g., computer use, television viewing, and videogame engagement) have become increasingly embedded in modern day culture, posing both physical and psychological health consequences (Babic et al., 2017; Goldfield et al., 2013). Despite the established link between recreational screen time and adolescent depressive symptomatology, little is known about mechanisms that may explain or influence this relationship. The overarching objective of the present dissertation, which includes two separate studies, was to examine cognitive, behavioural, affective, and interpersonal factors associated with the relationship between adolescents’ total daily recreational screen time activities and depressive symptomatology over time. The dissertation includes archival data from the Research on Eating and Adolescent Lifestyle (REAL) Study, which examined a large sample of students from the National Capital Region of Canada. Both Study 1 and Study 2 examined a subsample of these students. Given that exposure to screen time occupies up to 10 hours of Canadian children and adolescents’ waking hours (Active Healthy Kids Canada, 2013; Leatherdale & Ahmed, 2011; Leatherdale & Harvey, 2015), the independent variable examined in the model was total daily recreational screen time activities. Because trajectories of depressive symptomatology typically increase during adolescence (Duchesne & Ratelle, 2014), the dependent variable examined in the model was depressive symptomatology. The time points spanned over 7 years. The purpose of Study 1 was to test a prospective longitudinal path analysis model. The model examined the relationship between total daily recreational screen time at baseline (T0) and depressive symptomatology at Time 4 (T4), with body image and disordered eating behaviours at Time 2 (T2) as potential mediating variables. The final sample included 304 English-speaking students (194 females, Mage = 13.40 years, SD = 1.10). Total daily recreational screen time at T0 was significantly predictive of depressive symptomatology at T4. Appearance (dis)satisfaction at T2 mediated the relationship between total daily recreational screen time at T0 and depressive symptomatology at T4. Total daily recreational screen time at T0 was significantly predictive of emotional eating and decreased body image satisfaction at T2. Restrained eating and appearance satisfaction were negatively associated with depressive symptomatology at T4. Results were independent of age and depressive symptomatology at T0. The purpose of Study 2 was to test a longitudinal moderation model including total daily recreational screen time at T0 and depressive symptomatology at T4, with attachment style, coping style, and perceived social support at T0 as potential moderating variables. The final sample included 170 English-speaking students (106 females; Mage = 13.01, SD = 0.96). Contrary to expectation, attachment style, coping style, and perceived social support did not moderate the relationship between total daily recreational screen time at T0 and depressive symptomatology at T4. However, insecure attachment was identified as a risk factor for depressive symptomatology among males. A trend emerged in that avoidance-oriented coping appeared to be a risk factor for depressive symptomatology among females and a protective factor for males. There was also a three-way interaction between total daily recreational screen time, gender, and perceived social support. That is, when perceived social support was high, higher levels of total daily recreational screen time at T0 was associated with higher levels of depressive symptomatology at T4 for both males and females, but the relationship was significant for males only. Findings from the present dissertation offer important theoretical, methodological, and clinical implications.

No description available.

Previous research has shown that the subjective expenence of ease or difficulty evoked by memory retrieval operations can play an important role in shaping a range of people's judgments (e.g., Schwarz, 1998). Rather than basing their outputs on the products of the retrieval process, people use experiential cues to guide response generation. Extending work of this kind, the present research investigated the extent to which experiences associated with prior processing operations (e.g., memory encoding and memory retrieval) may affect people's judgments of elapsed time. In Experiments 1-5, participants committed material to memory under encoding conditions that varied in difficulty. Estimates were then taken of the duration and subjective difficulty of the encoding task. As predicted, the subjective ease or difficulty of prior processing operations was shown to guide people's retrospective duration judgments. Specifically, judgments of elapsed time were shorter under difficult processing conditions. In Experiments 6-8, this prediction was further supported when differential demands were placed on the memory retrieval process. That is, when retrieving information was experienced as difficult rather than easy, people judged that less time had elapsed. In Experiment 9, the same experiential effects emerged when immersive virtual environment technology was used to create a more dynamic task environment. These results are considered in the context of contemporary work on retrospective temporal estimation, with particular emphasis on the role of experiential factors in social cognition .

No description available.

The four decades that span the collapse of British imperial authority in the American colonies in 1774, to the disintegration of the Napoleonic Empire in 1815 witnessed unfathomable social and political change. There emerged a transformation from one ‘type’ of time to another: a change in the nature of change itself. Following the onset of the American and French Revolutions, time became more than a constitutive element in the lived experience of history – it also became the chief assassin of political legitimacy. Widespread considerations and perceptions of time in both American and French revolutionary contexts complicated and deranged the efficacy of power. Drawing upon contemporary temporal theories to explain how legitimate political authority eroded (before revolution), remained unstable (during revolution), and was finally reassembled (after revolution), this thesis presents two empirical case-studies for assessing the validity of German historian Reinhart Koselleck’s thesis, and other’s, regarding temporality and historicity. Although Koselleck’s viewpoint is largely dependent upon anecdote and abstraction to support theoretical observations, this thesis explores the application of time conceptions to five sites of political contestation: (1) the peculiar historicity of the ancien regime, which contributed to its own collapse by producing a time temperament that desensitised it to political urgency; (2) deliberative processes of the early Revolutions and the way in which time was transformed from an absolute or constant conceptual presence into an historical actor in its own right; (3) experimentations with time and history that were both a response to, and an attempt to rectify, the instability of political power during the mid-1780s in America and the early-1790s in France; (4) manipulations of revolutionary historical experience as a strategy for justifying the quasi-legal enterprises of the Constitutional Convention, 1787, and the coup of Brumaire, 1799; and (5) a comparative analysis of the interaction between power politics and temporality under the administration of George Washington and the Napoleonic Empire.

This thesis presents the design and the stability analysis of a hierarchical controller for unmanned aerial vehicles. We utilize non-linear control methodology to command dynamics of unmanned helicopter which has been divided into slower translational dynamics (outer-loop) and faster orientation dynamics (inner-loop), thus exhibiting hierarchical structure. The attitude angles and position which separately belongs to the inner-loop and the outer-loop can be independently controlled by backstepping control strategy. Stability analysis of the helicopter system including applying dynamics has been illustrated after designing. And relative comparison between linear and nonlinear controllers has been carried out. After studying linear control, nonlinear control and stability analysis of one small-scale helicopter, we think about control strategy of a group helicopter which can be called as consensus control.