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  • 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.
1071

Renewal and Memory Approaches to Study Biological and Physiological Processes

Tuladhar, Rohisha 05 1900 (has links)
In nature we find many instances of complex behavior for example the dynamics of stock markets, power grids, internet networks, highway traffic, social networks, heartbeat dynamics, neural dynamics, dynamics of living organisms, etc. The study of these complex systems involves the use of tools of non-linear dynamics and non-equilibrium statistical physics. This dissertation is devoted to understanding two different sources of complex behavior – non-poissonian renewal events also called crucial events and infinite memory of fractional Brownian motion. They both generate 1/f noise frequency spectrum. Thus, we studied examples of both processes and also their joint action. We also tried to establish the role of crucial events in biological and physiological processes like biophoton emission during the germination of seeds, the dynamics of heartbeat and neural dynamics. Using a statistical method of analyzing the time series of bio signals we were able to quantify the complexity associated with the underlying dynamics of these processes. Finally, we adopted a model that unifies both crucial events and memory fluctuations to study the rhythmic behavior observed in heart rate variability of people during meditation. We were able to also quantify the level of stress reduction during meditation. The work presented in this dissertation may help us understand the communication and transfer of information in complex systems.
1072

Disasters, Smart Growth and Economic Resilience: An Empirical Analysis of Florida Cities

Chatterjee, Vaswati 08 1900 (has links)
This dissertation examines the relationship between economic resilience, disaster experience, and smart growth policies at the local government level. The study is based upon three research questions that examine spatial distribution of economic resilience in Florida cities, and examines the impact of disaster experience, and smart growth policies adopted by local governments on economic resilience. Based upon the bounce-forward approach (Cowell, 2013; Klein et al. 2003), economic resilience is defined using three dimensions—economic stability, economic equity, and economic diversity. The spatial analysis is conducted by mapping economic resilience scores across 780 Census Designated Places in Florida through standard deviation method of classification, and conducting cluster-outlier analysis. Results suggest difference in economic resilience within coastal and inland communities—with higher scores mostly situated inland. East Central Florida, Tampa Bay, and South Florida were identified as high economic resilience clusters, and Northwest Florida was identified as low resilience cluster. Impact of disaster experience, and smart growth policies on economic resilience was examined based upon logic of focusing events by Birkland (1997, 2010). Data was collected from the U.S. Census, the National Climatic Data Center, and the Energy Sustainable Florida Communities Survey conducted by Florida State University in 2009. Results suggest significant association between disaster experience of communities and their level of economic resilience, highlighting the importance of community learning in building capacity for resilience after disasters. The results also highlight the need of balancing mitigation and adaptation strategies. Mixed-use development policies, green building certification, and energy savings policies were found to have a significant positive impact on economic resilience.
1073

Changes in benthic productivity and community composition following silver carp die offs: a mesocosm approach

Bowman, Jacob 01 December 2024 (has links) (PDF)
Invasive species are often both ecologically and economically detrimental, particularly in freshwater ecosystems where direct and indirect impacts of invasion interact with pre-existing anthropogenic stressors to magnify consequences for native communities and habitats. Planktivorous silver carp (Hypophthalmichthys molitrix) are invasive in the Mississippi River watershed, where their daily consumption of detrital seston can total more than half their body mass, and where they outnumber all native species combined in some river reaches. Because of these astonishing abilities, silver carp can cause basal resource changes, altering the body sizes and abundances of native plankton communities upon invasion. Much research has focused on this outcome of silver carp proliferation, but investigation into other effects of their presence in invaded systems has not received the same attention. Despite the unique tendency of silver carp to experience species-specific mass-mortality events, for example, there is a dearth of peer-reviewed evaluation of the possible ecological consequences of these occurrences. To elucidate the effects of these events which can comprise hundreds of thousands of individuals, we determined how the decomposition of silver carp carcasses following mass-mortality events affected benthic invertebrate community composition and productivity using a mesocosm approach. Each mesocosm was subjected to either the presence or absence of a silver carp carcass over the length of an eight-week experiment. Carcass presence created anoxic conditions in the mesocosms and acutely increased benthic invertebrate biomass and benthic periphyton growth. While acute, changes to benthic conditions following silver carp mass-mortality events are likely to have long-term effects in both invaded freshwater systems and their surrounding terrestrial landscapes. Given the magnitude of die-offs, it is possible that these events could cause ecosystem-level alterations. Further research, therefore, is needed into the additional impacts that may follow carcass decomposition to quantify and predict outcomes associated with continued silver carp invasion.
1074

Tracing the Evolution of Collaborative Virtual Research Environments: A Critical Events-Based Perspective

Trudeau, Ashley B 08 1900 (has links)
A significant number of scientific projects pursuing large scale, complex investigations involve dispersed research teams, which conduct a large part or their work virtually. Virtual Research Environments (VREs), cyberinfrastructure that facilitates coordinated activities amongst dispersed scientists, thus provide a rich context to study organizational evolution. Due to the constantly evolving nature of technologies, it is important to understand how teams of scientists, system developers, and managers respond to critical incidents. Critical events are organizational situations that trigger strategic decision making to adjust structure or redirect processes in order to maintain balance or improve an already functioning system. This study examines two prominent VREs: The United States Virtual Astronomical Observatory (US-VAO) and the HathiTrust Research Center (HTRC) in order to understand how these environments evolve through critical events and strategic choices. Communication perspectives lend themselves well to a study of VRE development and evolution because of the central role occupied by communication technologies in both the functionality and management of VREs. Using the grounded theory approach, this study uses organizational reports to trace how critical events and their resulting strategic choices shape these organizations over time. The study also explores how disciplinary demands influence critical events.
1075

Efektivita Public Relations v českých prezidentských volbách 2013 / Public relations effectiveness in the czech presidential elections 2013

Šťastná, Alžběta January 2015 (has links)
This thesis Public Relations Effectiveness in the Czech Presidential Elections 2013 analyzes the effectiveness of public relations tools that have a key influence in building of positive image of candidates in political elections, and on the particular case of the Karel Schwarzenbergs election campaign in first ever presidential election in the Czech Republic. The first part deals with the theoretical definition of public relations in general and subsequently in the narrower sense in relation to politics, adaptation to the specific needs of political communication for example in endorsement or positive and negative campaigns in electoral contests. Attention is also paid to the possibilities of cooperation with the media, agenda setting and framing. In the second practical part is first introduced the background of the presidential election together with a detailed profile of Karel Schwarzenberg, followed by an analysis of his electoral campaign between August 2012 and January 2013, and in terms of effectiveness of various public relations tools that were used in the campaign and their success in projecting into the media content.
1076

Agent-based modelling and simulation of pedestrian evacuation behaviour during large outdoor events: fireworks to display at Tsim Sha Tsui of Hong Kong as a case study. / CUHK electronic theses & dissertations collection

January 2011 (has links)
By conducting a field survey to collect and investigate the attributes and behaviour patterns of participants in the case event, the proposed model and simulation system were implemented. Three scenarios of different populations of involved agents were simulated on the finished system according to the sample data. Simulation results were analyzed and compared to the observed data. The simulation system was found to be capable of reproducing compatible dynamics of pedestrian flows. / Finally the conclusions of this thesis study were presented. / In order to implement the model, the layered behavioural simulation model was proposed for putting the decisions made from the behaviour model into action. By identifying the three layers sustaining the routing procedure at their respective levels, the evacuation route was finally converted to selecting stepping cells from adjacent neighbours. In this way a quick way-finding process can be achieved toward the ultimate destination, so that the global objectives are coordinated with local action decisions on the cell scale. With this simulation model, the framework of the geo-referenced agent-based system was proposed with technical details presented. This system was built directly on a GIS base and thus was able to conduct simulation in a real space environment and perform advanced GIS analysis inside the simulation. / In reviewing the existing evacuation models and simulation systems, it was found that although there have been remarkable advances in reproducing and analyzing many phenomena and the dynamics of pedestrian flow in evacuations, social psychological factors were not well considered. Theories and research in the social psychological field have indicated that these factors are essential in evacuation behaviour. Therefore the author examined the socio-economic factors relating to psychological responses through a literature review and explored the potential for integrating such factors into the agent based modelling approach. / Inspired by such concerns, the author proposed the individual cognitive behaviour model consisting of the Personalized Spatial Cognitive Road Network, which represents the diverse individual spatial knowledge of recognizable roads, and the Multiple Routing Strategies which incorporated individual preferences in selecting routing strategy. The proposed model follows the principle that pedestrians are considered to be composed of heterogeneous individuals, thus each pedestrian could have his or her own knowledge base and rules of behaviour. Two steps in constructing each component were presented respectively, with an integrated framework presented in the context of agent based modelling. / Public safety has become more and more important nowadays as tragic incidents, such as the 9/11 World Trading Centre attack, have caused a large number of causalities. It is critical to improve the capability of the security department for safely managing the crowd in response to an emergency. Conventional techniques investigating evacuation dynamics, such as the sand-box game utilized by Hong Kong police department preparing evacuation plans for the case event, are generally inadequate for providing sufficient support to crowd management. Enhancing the management practice by computer based simulation techniques has been attracting an increasing amount of research interests recently, as it can offer timely decision making assistance in changing situations compared to the conventional approaches. / Wu, Lei. / Advisers: Hui Lin; Bo Huang; Yee Leung. / Source: Dissertation Abstracts International, Volume: 73-06, Section: A, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 249-273). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.
1077

Estratégias de computação seqüenciais e paralelas sobre espaços coerentes / Sequential and parallel computational strategies of coherence spaces

Schneider Sellanes, Ruben Gerardo January 1996 (has links)
As estruturas de dados concretas (cds) são quaternas (C, V, E, l-) que contêm um conjunto C de células, um conjunto V de valores, um conjunto E de eventos e uma relação de habilitação l-. O conjunto de estados de uma cds é um domínio concreto que pode ser considerada a parte "abstrata" das cds. Da mesma maneira tem-se que os domínios de eventos (que são generalizações dos domínios concretos) são a parte abstrata das estruturas de eventos. Mostra-se a relação dos domínios concretos e domínios de eventos com os espaços coerentes, assim como também das teias de espaços coerentes com as cds e estruturas de eventos. Intuitivamente, uma cds é uma teia de um espaço coerente se toda célula c de C não é habilitada por nenhum evento (ou equivalentemente, é habilitada pelo conjunto vazio), isto é, V C E C, 0 F c. Outra forma de expressar isto é dizer que uma cds e uma teia de um espaço coerente se o conjunto de estados da cds é um espaço coerente. Definem-se os algoritmos lineares como sendo estados de uma cds no estilo dos algoritmos seqüenciais do Curien ([CUR 86]). Em particular as cds consideradas são teias de espaços coerentes. Mostra-se como obter a cds !A—>B, a partir de uma função estável f. A —> B. O algoritmo linear desta cds possui todas as estratégias de computação (seqüenciais e paralelas) que computam a função subjacente f, o que implica que os algoritmos lineares podem ser considerados meta-algoritmos. Mostra-se que para toda estratégia de computação seqüencial de um algoritmo linear, existe um algoritmo seqüencial de Curien que computa a mesma função, e vice-versa. A definição de estratégia de computação é dada de maneira tal que permite se dar semântica a segmentos de programas. Define-se uma operação de composição de estratégias, de forma tal que se pode obter uma estratégia de computação de um programa, a partir da composição das estratégias dos segmentos. / The concrete data structures, or cds, (C, V, E, l-) consists of a set C of cells, a set V of values. a set E of events and an enabling relation l-. The set of states of a cds is a concrete domain, that can be considered the "abstract" counterpart of the cds. In the same way we have that the events domains (that are more general that the concretes domains) are the abstract counterpart of the events structures. We show the relation between the concretes domains and events domains with the coherence spaces, as just as the relation between the cds and events structures with webs of coherence spaces. Intuitivelly, a cds is a web of a coherence space if any cell c is not enabled for any event, i.e. Vce C, 0 F c. We can say that a cds is a web of a coherence space if the set of states of the cds is a coherence space. We define the linear algorithms as states of a cds following the Curien's sequential algorithms ([CUR 86]). In particular the cds considered are webs of coherence spaces. We show how to obtain a cds !A—>B from a stable function f. A —> B. The linear algorithm of this cds contain all the computational strategies (sequentials and parallels) that compute the subjacent function f; this implies that the linear algorithms can be considered a kind of meta-algorithms. We show that for all sequential computational strategy of a linear al gorithm exists a Curien's sequential algorithm that compute the same function and conversely. We define the computational strategies in such a way that we can give semantic of segments of programs. We define a composition operation for strategies. This operation has the advantage that we can obtain the computational strategy of a program as the composition of the segments of it.
1078

Cognitive coping and depression in elderly long-term care residents

McCormick, Christine Viola 01 January 2007 (has links)
The purpose of this research was to examine specific coping methods used by the elderly as they adjust to the environment of a long-term care facility, and to examine the correlations between these coping methods and levels of depressive symptomatology.
1079

A Duration Analysis of Food Safety Recall Events in the United States: January, 2000 to October, 2009

Joy, Nathaniel Allen 2010 December 1900 (has links)
The safety of the food supply in the United States has become an issue of prominence in the minds of ordinary Americans. Several government agencies, including the United States Department of Agriculture and the Food and Drug Administration, are charged with the responsibility of preserving the safety of the food supply. Food is withdrawn from the market in a product recall when tainted or mislabeled and has the potential to harm the consumer in some manner. This research examines recall events issued by firms over the period of January, 2000 through October, 2009 in the United States. Utilizing economic and management theory to establish predictions, this study employs the Cox proportional hazard regression model to analyze the effects of firm size and branding on the risk of recall recurrence. The size of the firm was measured in both billions of dollars of sales and in thousands of employees. Branding by the firm was measured as a binary variable that expressed if a firm had a brand and as a count of the number of brands within a firm. This study also provides a descriptive statistical analysis and several findings based on the recall data specifically relating to annual occurrences, geographical locations of the firms involved, types of products recalled, and reasons for recall. We hypothesized that the increasing firm size would be associated with increased relative risk of a recall event while branding and an increasing portfolio of brands would be associated with decreased relative risk of a recall event. However, it was found that increased firm size and branding by the firm are associated with an increased risk of recall occurrence. The results of this research can have implications on food safety standards in both the public and private sectors.
1080

Estratégias de computação seqüenciais e paralelas sobre espaços coerentes / Sequential and parallel computational strategies of coherence spaces

Schneider Sellanes, Ruben Gerardo January 1996 (has links)
As estruturas de dados concretas (cds) são quaternas (C, V, E, l-) que contêm um conjunto C de células, um conjunto V de valores, um conjunto E de eventos e uma relação de habilitação l-. O conjunto de estados de uma cds é um domínio concreto que pode ser considerada a parte "abstrata" das cds. Da mesma maneira tem-se que os domínios de eventos (que são generalizações dos domínios concretos) são a parte abstrata das estruturas de eventos. Mostra-se a relação dos domínios concretos e domínios de eventos com os espaços coerentes, assim como também das teias de espaços coerentes com as cds e estruturas de eventos. Intuitivamente, uma cds é uma teia de um espaço coerente se toda célula c de C não é habilitada por nenhum evento (ou equivalentemente, é habilitada pelo conjunto vazio), isto é, V C E C, 0 F c. Outra forma de expressar isto é dizer que uma cds e uma teia de um espaço coerente se o conjunto de estados da cds é um espaço coerente. Definem-se os algoritmos lineares como sendo estados de uma cds no estilo dos algoritmos seqüenciais do Curien ([CUR 86]). Em particular as cds consideradas são teias de espaços coerentes. Mostra-se como obter a cds !A—>B, a partir de uma função estável f. A —> B. O algoritmo linear desta cds possui todas as estratégias de computação (seqüenciais e paralelas) que computam a função subjacente f, o que implica que os algoritmos lineares podem ser considerados meta-algoritmos. Mostra-se que para toda estratégia de computação seqüencial de um algoritmo linear, existe um algoritmo seqüencial de Curien que computa a mesma função, e vice-versa. A definição de estratégia de computação é dada de maneira tal que permite se dar semântica a segmentos de programas. Define-se uma operação de composição de estratégias, de forma tal que se pode obter uma estratégia de computação de um programa, a partir da composição das estratégias dos segmentos. / The concrete data structures, or cds, (C, V, E, l-) consists of a set C of cells, a set V of values. a set E of events and an enabling relation l-. The set of states of a cds is a concrete domain, that can be considered the "abstract" counterpart of the cds. In the same way we have that the events domains (that are more general that the concretes domains) are the abstract counterpart of the events structures. We show the relation between the concretes domains and events domains with the coherence spaces, as just as the relation between the cds and events structures with webs of coherence spaces. Intuitivelly, a cds is a web of a coherence space if any cell c is not enabled for any event, i.e. Vce C, 0 F c. We can say that a cds is a web of a coherence space if the set of states of the cds is a coherence space. We define the linear algorithms as states of a cds following the Curien's sequential algorithms ([CUR 86]). In particular the cds considered are webs of coherence spaces. We show how to obtain a cds !A—>B from a stable function f. A —> B. The linear algorithm of this cds contain all the computational strategies (sequentials and parallels) that compute the subjacent function f; this implies that the linear algorithms can be considered a kind of meta-algorithms. We show that for all sequential computational strategy of a linear al gorithm exists a Curien's sequential algorithm that compute the same function and conversely. We define the computational strategies in such a way that we can give semantic of segments of programs. We define a composition operation for strategies. This operation has the advantage that we can obtain the computational strategy of a program as the composition of the segments of it.

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