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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.
31

Multi-Species Influenza Models with Recombination

Coburn, Brian John 26 March 2009 (has links)
Avian influenza strains have been proven to be highly virulent in human populations, killing approximately 70 percent of infected individuals. Although the virus is able to spread across species from birds-to-humans, some strains, such as H5N1, have not been observed to spread from human-to-human. Pigs are capable of infection by both avian and human strains and seem to be likely candidates as intermediate hosts for co-infection of the inter-species strains. A co-infected pig potentially acts as a mixing vessel and could produce a new strain as a result of a recombination process. Humans could be immunologically naive to these new strains, hence making them super-strains. We propose an interacting host system (IHS) for such a process that considers three host species that interact by sharing strains; that is, a primary and secondary host species can both infect an intermediate host. When an intermediate host is co-infected with the strains from both the other hosts, co-infected individuals may become carriers of a super-strain back into the primary host population. The model is formulated as a classical susceptible-infectious-susceptible (SIS) model, where the primary and intermediate host species have a super-infection and co-infection with recombination structure, respectively. The intermediate host is coupled to the other host species at compartments of given infectious subclasses of the primary and secondary hosts. We use the model to give a new perspective for the trade-off hypothesis for disease virulence, by analyzing the behavior of a highly virulent super-strain. We give permanence conditions for a number of the subsystems of the IHS in terms of basic reproductive numbers of independent strains. We also simulate several relevant scenarios showing complicated dynamics and connections with epidemic forecasting.
32

none

Lin, Po-heng 09 August 2007 (has links)
This research evaluates whether the persistence of mutual fund performance is related to the momentum effect of stock returns. Empirical results reveal that, regardless of which time horizon we analyze, the positive performance of mutual funds tends to persist. The persistence of mutual fund performance, however, is not related to the momentum effect, which is measured by the momentum variable, either PR0.5YR or PR1YR. We conclude that the momentum effect of stock returns does not account for the persistence of mutual fund performance.
33

Determinants of Object Persistence: The Role of Cue Type, Cue Duration and Cue Strength

Wartak, Szymon January 2008 (has links)
Four experiments investigated object persistence in conscious awareness as a function of the nature of the cues that permit the object to be segregated from the background, and identified. A number of factors were manipulated (cue type, [color, motion, color & motion] cue duration after object identification [1s vs 5s] and cue strength [strong vs weak]). Performance was fractionated into identification, maintenance and persistence components. The results show that (1) stronger cues yielded faster identification, and (2) persistence was independent of identification time, and (3) motion cues were associated with longer persistence than color cues. A distinction between dorsal and ventral visual pathways as used to segregate the object from the background provides one way to organize the data.
34

Determinants of Object Persistence: The Role of Cue Type, Cue Duration and Cue Strength

Wartak, Szymon January 2008 (has links)
Four experiments investigated object persistence in conscious awareness as a function of the nature of the cues that permit the object to be segregated from the background, and identified. A number of factors were manipulated (cue type, [color, motion, color & motion] cue duration after object identification [1s vs 5s] and cue strength [strong vs weak]). Performance was fractionated into identification, maintenance and persistence components. The results show that (1) stronger cues yielded faster identification, and (2) persistence was independent of identification time, and (3) motion cues were associated with longer persistence than color cues. A distinction between dorsal and ventral visual pathways as used to segregate the object from the background provides one way to organize the data.
35

The Dynamic Analysis of Taiwan Money Demand Function-Impulse Response Analysis in Infinite Order Cointegrated Vector Autoregressive Processes

Chang, Shien-Lin 19 July 2000 (has links)
none
36

A Study on the Decomposition of Characteristic Ability of Mutual Fund Performance and Persistence

Chiang, I-Hsing 26 June 2001 (has links)
none
37

Postsecondary enrollment delay and associated persistence outcomes

Gururaj, Suchitra V. 06 July 2012 (has links)
As exposure to college becomes increasingly integral to individual growth and societal economic vitality, the delay of postsecondary enrollment may be undertaken at a cost to both the individual and society. In addition, this delay represents a rupture in an ideally seamless P-16 educational continuum. Using a combined model of college choice adjusted to account for immediate versus delayed enrollment as well as persistence and graduation, this study addressed whether a student’s postsecondary enrollment delay may contribute to his or her persistence or inability to persist once enrolled in college. To this end, a unique dataset was constructed to reflect student profiles from high school through college and was used to analyze the college-going behaviors of the 2004 cohort of Texas public high school graduates, as well as their participation in the workforce. Descriptive statistics were assembled to characterize immediate enrollers in contrast to delayed enrollers, especially in regard to demographic characteristics and academic preparation. The role of delay in college persistence was measured through the undertaking of eight logistic regression models that accounted for the role of demographic characteristics, academic preparation, and higher education institutional choice, along with the delay factor, on persistence. Findings revealed that students considered at-risk and who are from minority groups are likely to delay enrollment. As well, students who are less academically prepared are overrepresented among delayers. The results of the logistic regression models reveal, moreover, that whatever disadvantage these particular groups experienced in regard to enrolling in postsecondary education, it may have been exacerbated by their delayed enrollment: delayers, in all models, were less likely to persist in college once they enrolled. For the policymaker, educator, or P-16 administrator, this study underscores the need to ensure that students’ academic careers receive early and frequent intervention, in case they decide they wish to enroll in college after graduation. Groups that lack certain types of social capital that facilitate access to postsecondary education ought to be provided appropriate counseling. Above all, the study highlights that access to college is simply not enough if college completion is as important as college enrollment. / text
38

Self-esteem and persistence in the face of failure

Di Paula, Adam 11 1900 (has links)
Two studies tested a theory of how trait self-esteem moderates behavioral and cognitive persistence in the face of failure. Three primary hypotheses were examined. First, that high self-esteem (HSE) individuals persist more than low self-esteem (LSE) individuals when their initial attempts to reach a goal fail, but subsequent or repeated failures lead HSE individuals to reduce behavioral persistence and pursue goal alternatives more quickly than LSE individuals. Second, that when no goal alternatives are available, HSE individuals behaviorally persist more than LSE individuals. Third, despite reductions in behavioral persistence, LSE individuals do not "give up" on the failed goal but continue to persist cognitively, in the form of aversive ruminations about the failed goal. In a factorial experiment, persistence was examined as a function of self-esteem, degree of failure, and the availability of goal alternatives. As hypothesized, HSE participants behaviorally persisted more than LSE participants after a single failure, but less after repeated failure. However, selfesteem differences in behavioral persistence did not emerge when goal alternatives were unavailable. Partial support was received for the hypothesis that LSE individuals engage in more ruminative persistence than HSE individuals-LSE participants showed higher levels of ruminative persistence on one of two measures of ruminative persistence. The findings regarding behavioral persistence were conceptually replicated, and the hypothesis regarding ruminative persistence received stronger support, in a longitudinal field study in which HSE and LSE participants initially listed their goals and reported on their behavioral and ruminative persistence regarding these goals 5 months later. HSE participants exhibited better calibration between perceptions of goal failure and behavioral pursuit than LSE participants, indicating that increasing perceptions of goal failure were associated with reductions in behavioral pursuit more for HSE than LSE participants. Although they reduced behavioral pursuit relative to HSE participants, LSE participants continued to persist cognitively, by ruminating about their goals more than HSE participants. Discussion focuses on the need to revise traditional views of HSE individuals that emphasize their tenacious persistence and views of LSE individuals that emphasize their tendency to give up in the face of failure.
39

Migration of objects during rapid serial visual search

Wilson, Keith Winston January 1995 (has links)
This thesis is concerned with the various factors determining the apparent migration of targets during rapid serial visual presentation (RSVP). This migration effect occurs when an observer reports a target as being present in a scene other than the one in which it was actually presented, usually the immediately preceding or following scene - the "host" scene. An experimental technique was developed based on Intraub's (1985;1989) work on these migration errors, and an improved computer-based system was developed. This allowed flexibility in the manipulation of experimental variables and also used a recognition memory paradigm to identify targets. Ten experiments were completed in total which examined three major issues concerning RSVP: contextual effects, low-level cues and the effects of apparent contrast. Using the newly developed software, Intraub's original results were replicated and extended. Manipulation of contextual information surrounding a host scene showed that the direction of apparent target migration, to the scene either succeeding or preceding the host scene, could be influenced by using a pre- or post-host bias in the visual context. For example, preceding an outdoor host-scene with another outdoor scene and following it with an indoor scene led to more migration errors to the preceding scene, i.e. there was a tendency for errors to be biased to structurally similar scenes. In another set of experiments, it was found that low-level binding cues could effectively aid the cohesiveness of host and target and thus reduce the number of migration errors. Furthermore, in a third set of experiments evidence that the direction of migration errors could be influenced by the apparent contrast of the search target was found. Higher apparent contrast could produce a predominance of pre-host migration errors. However, caution is called for in the interpretation of this final set of results since they are somewhat ambiguous and need further clarification. Taken as a whole the results found in these experiments have shown that an overall presentation rate of 8.33 Hz, subjects are able to effectively grasp the gist of the background to the target.
40

Medlares egenskaper : Hur påverkas förhandlingsparterna av medlarens envishet och tålamod?

Strandberg, Johanna, Hjalmarsson, Emma January 2015 (has links)
Abstract Title: The Mediator’s Qualities - How are the negotiating parties effected by the mediator's persistence and patience? Level: Final assignment for Bachelor Degree Author: Johanna Strandberg and Emma Hjalmarsson Supervisor: Jens Eklinder Frick and Jonas Molin Date: May 2015 Aim: Our aim is to create a greater understanding of the negotiating parties' experience of the mediator's persistence and patience. Method: We have chosen a deductive approach that we have based our empirical data on already existing research. Theoretical material has been gathered through literature, theses and scientific articles. With the background to our aim, we have chosen to use a qualitative approach where we have interviewed ten people who have been in contact with a real estate agent the last 24 months. The empirical data was then analysed and discussed in our analysis and conclusion. Result & Conclusions: We have found that the mediator's persistence and patience affect negotiating partners in various ways. Patient is seen as a positive quality while persistence can be perceived as negative. Our survey shows that when persistence and patience are combined, the result is successful. Our survey also showed that the main characteristics of the mediator were not at all persistence and patience, which earlier research has shown, but instead it was nice, impartial and knowledgeable. Suggestions for further research: What we think would be interesting for further research is to investigate the mediator's perspective because we only looked at the negotiating parties' perspective. We would encourage further research on qualities in general and also on the specific persistence and patience because we fount that it was a limited amount of research based on these qualities. Contribution of the thesis: The contribution of this study is that it has created a larger understanding for the characteristics that negotiation parties perceive as important for a real estate agent. This can be beneficial for real estate agents to know what properties the parties prefer and how they should act in their efforts to make the parties satisfied. Key words: Negotiation, mediation, characteristics, persistence, patience.

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