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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.
351

Essays on Political and Fiscal Decentralization

Qibthiyyah, Riatu M 22 August 2008 (has links)
We address the questions on what determines local government proliferation, specifically on the impact of intergovernmental transfers on proliferation. On exploring the determinants of proliferation, we provide a more elaborate empirical technique than exists in the literature by employing panel binary outcome, survival regression, as well as count analysis to capture the time varying effect from intergovernmental transfers. We also examine the impact of proliferation on service delivery outcomes and construct channels by which the policy may affect the outcomes in the education and health sectors. We apply panel difference-in-difference estimation and we uniquely identify the different treatment group and thus control for the plausible differential impact on outcomes in regards to changes in intergovernmental transfers. On the determinants of local government formation, there are likely competing effects across transfers on the decision to proliferate as well as on the extent of fragmentation given that we find (1) the lump-sum conditional grants positively influence the probability of proliferation, (2) a province with higher median share of equalization grants associates with higher number of local governments, (3) higher equalization grants implies a longer duration to the proliferation event, and (4) higher tax sharing in the proliferated local governments reflects higher stability where stability refers to the longer duration to the sequential proliferation event. The findings suggest the tactical central-local behavior may be present, however, the support of rent-seeking hypothesis on proliferation should not be generalized to overall system of transfers. On the impact from the proliferation policy, the education and health outcomes estimations provide mixed results within the treatment group. The findings shed light on the current practice of administrative or political decentralization, specifically on the competing local-central preferences within each sector on measured service delivery outcomes. The results from difference-in-difference (DID) estimations show support on attainment of education outcome in new local governments represented by a reduction in the dropout rate but not on the quality of education in terms of higher students’ tests scores even though there is a relatively higher conditional grants allocated to the proliferated local governments. Meanwhile, in terms of infant mortality rate, we only find evidence of improvement in infant mortality on the originating local government but not on the new local governments. Controlling for selectivity and production function covariates have not changed the pattern of the impact.
352

Identifying determinants of HIV disease progression in Saskatoon, Saskatchewan

Konrad, Stephanie 23 September 2011
Context & Rationale: Individuals with similar CD4 cell counts and RNA levels can vary considerably with regards to clinical progression. This variation is likely the result of a complex interplay between viral, host and environmental factors. This study aimed to characterize and identify predictors associated with disease progression to AIDS or death in Saskatoon, Saskatchewan. Methods: This is a retrospective cohort study of 343 seroprevalent HIV positive patients diagnosed from Jan 2005 to Dec 2010. Of these, 73 had an estimated seroconversion date. Data was extracted from medical charts at two clinics specialized in HIV/AIDS care. Disease progression was measured as time from HIV diagnosis (or seroconversion) to immunological AIDS and death. The Cox hazard model was used. Results: The 3-year and 5-year immunological AIDS free probability was 53% and 33%, respectively. The 3-year and 5-year survival probability was 89% and 77%, respectively. Among the seroconversion cohort, the 3-year immunological AIDS free probability was 76%. Due to multicollinearity, separate models were built for IDU, hepatitis C and ethnicity. A history of IDU (HR, 3.0; 95%CI, 1.2-7.1), hepatitis C coinfection (HR, 2.9; 95%CI, 1.2-6.9), baseline CD4 counts (HR, 0.95; 95%CI, 0.92-0.98, per ever 10 unit increase), ever on ART, and year of diagnosis were significant predictors of progression to immunological AIDS among the seroprevalent cohort. Age at diagnosis, sex and ethnicity were not. For survival, only treatment use was a significant predictor (HR, 0.34; 95%CI, 0.1-0.8). Hepatitis C coinfection was marginally significant (p=0.067), while a history of IDU, ethnicity, gender, age at diagnosis, and year of diagnosis were not. Among the seroconversion cohort, no predictors of progression to immunological AIDS were identified. Ethnicity, hepatitis C coinfection and history of IDU could not be assessed. Conclusion: Our study found that IDU, HCV coinfections, baseline CD4 counts, and ART use were significant predictors of disease progression. This highlights the need for increased testing and early detection and for targeted interventions for these particularly vulnerable populations to slow disease progression.
353

Statistical modeling of longitudinal survey data with binary outcomes

Ghosh, Sunita 20 December 2007
Data obtained from longitudinal surveys using complex multi-stage sampling designs contain cross-sectional dependencies among units caused by inherent hierarchies in the data, and within subject correlation arising due to repeated measurements. The statistical methods used for analyzing such data should account for stratification, clustering and unequal probability of selection as well as within-subject correlations due to repeated measurements. <p>The complex multi-stage design approach has been used in the longitudinal National Population Health Survey (NPHS). This on-going survey collects information on health determinants and outcomes in a sample of the general Canadian population. <p>This dissertation compares the model-based and design-based approaches used to determine the risk factors of asthma prevalence in the Canadian female population of the NPHS (marginal model). Weighted, unweighted and robust statistical methods were used to examine the risk factors of the incidence of asthma (event history analysis) and of recurrent asthma episodes (recurrent survival analysis). Missing data analysis was used to study the bias associated with incomplete data. To determine the risk factors of asthma prevalence, the Generalized Estimating Equations (GEE) approach was used for marginal modeling (model-based approach) followed by Taylor Linearization and bootstrap estimation of standard errors (design-based approach). The incidence of asthma (event history analysis) was estimated using weighted, unweighted and robust methods. Recurrent event history analysis was conducted using Anderson and Gill, Wei, Lin and Weissfeld (WLW) and Prentice, Williams and Peterson (PWP) approaches. To assess the presence of bias associated with missing data, the weighted GEE and pattern-mixture models were used.<p>The prevalence of asthma in the Canadian female population was 6.9% (6.1-7.7) at the end of Cycle 5. When comparing model-based and design- based approaches for asthma prevalence, design-based method provided unbiased estimates of standard errors. The overall incidence of asthma in this population, excluding those with asthma at baseline, was 10.5/1000/year (9.2-12.1). For the event history analysis, the robust method provided the most stable estimates and standard errors. <p>For recurrent event history, the WLW method provided stable standard error estimates. Finally, for the missing data approach, the pattern-mixture model produced the most stable standard errors <p>To conclude, design-based approaches should be preferred over model-based approaches for analyzing complex survey data, as the former provides the most unbiased parameter estimates and standard errors.
354

Brood ecology and population dynamics of King Eiders

Mehl, Katherine Rose 14 July 2004
Birth and death processes and the extent of dispersal directly affect population dynamics. Knowledge of ecological factors that influence these processes provides insight into natural selection and understanding about changes in population size. King eiders (Somateria spectabilis) breed across the arctic region of North America and winter in polar oceanic waters of the western and eastern regions of the continent. Here I studied a local population of King Eiders at Karrak Lake, Nunavut, where I used analysis of naturally-occurring stable isotopes (13C, 15N) from feathers, in conjunction with banding data, to investigate the extent of dispersal among winter areas and the influence of winter area on subsequent breeding. In addition, I used capture-mark-recapture methods to (1) investigate the relative contributions of survival and recruitment probabilities to local population dynamics, and (2) to test hypotheses about the influence of specific ecological factors on those probabilities or their components, e.g., nest success, duckling survival. Isotopic data suggested that female King Eiders were not strongly philopatric to wintering areas between years. Individuals that wintered in western seas initiated nests earlier and had slightly larger clutch sizes during early nest initiation relative to females that wintered in the east. Female condition during incubation did not vary by winter area. Female King Eiders of known breeding age were at least 3-years-old before their first breeding attempt. Age of first successful breeding attempt did not appear to be influenced by body size. However, after reaching breeding age, larger females apparently experienced greater breeding propensity. Adult survival rate (1996-2002) was estimated as 0.87 and recapture probabilities varied with time and ranged from 0.31 to 0.67. There is no evidence of survival advantages related to larger size. Population growth for this local study area was high, estimated at 20%/year with larger females contributing more to the population growth than smaller females. With continued population growth, density-dependent effects on components of recruitment appeared to emerge; the proportion of the female population that nested successfully declined with increasing population size. The probability of breeding successfully did not correlate with Mayfield estimates of nest success. To gain insight into King Eider brood ecology I, respectively, monitored 111 and 46 individually-marked ducklings from broods of 23 and 11 radio-marked King Eiders during 2000 and 2001. Total brood loss accounted for 84% of all duckling mortality with most brood loss (77%) less than 2 days after hatch. Estimated apparent survival rates of ducklings to 22 days of age were 0.10 for those that remained with radio-marked females, 0.16 for all ducklings, including those that had joined other broods, and 0.31 for broods. Ducklings brooded by larger females experienced higher survival than those brooded by smaller females, and ducklings that hatched earlier in the breeding season survived at higher rates. Overland brood movements of 1 km or more occurred in both years, and survival was greatest for ducklings that dispersed from Karrak Lake to smaller ponds than on Karrak Lake itself, the central nesting area. Estimates of duckling survival, combined with relative contributions to the population by adults, suggest that ecological factors such as body size can influence population growth. Furthermore, low duckling survival and delayed maturity, emphasize the need of high adult survival for population growth to occur. These data, in combination with evidence of dispersal among wintering areas have helped contribute to a broader understanding of North American King Eider demographics.
355

Identifying determinants of HIV disease progression in Saskatoon, Saskatchewan

Konrad, Stephanie 23 September 2011 (has links)
Context & Rationale: Individuals with similar CD4 cell counts and RNA levels can vary considerably with regards to clinical progression. This variation is likely the result of a complex interplay between viral, host and environmental factors. This study aimed to characterize and identify predictors associated with disease progression to AIDS or death in Saskatoon, Saskatchewan. Methods: This is a retrospective cohort study of 343 seroprevalent HIV positive patients diagnosed from Jan 2005 to Dec 2010. Of these, 73 had an estimated seroconversion date. Data was extracted from medical charts at two clinics specialized in HIV/AIDS care. Disease progression was measured as time from HIV diagnosis (or seroconversion) to immunological AIDS and death. The Cox hazard model was used. Results: The 3-year and 5-year immunological AIDS free probability was 53% and 33%, respectively. The 3-year and 5-year survival probability was 89% and 77%, respectively. Among the seroconversion cohort, the 3-year immunological AIDS free probability was 76%. Due to multicollinearity, separate models were built for IDU, hepatitis C and ethnicity. A history of IDU (HR, 3.0; 95%CI, 1.2-7.1), hepatitis C coinfection (HR, 2.9; 95%CI, 1.2-6.9), baseline CD4 counts (HR, 0.95; 95%CI, 0.92-0.98, per ever 10 unit increase), ever on ART, and year of diagnosis were significant predictors of progression to immunological AIDS among the seroprevalent cohort. Age at diagnosis, sex and ethnicity were not. For survival, only treatment use was a significant predictor (HR, 0.34; 95%CI, 0.1-0.8). Hepatitis C coinfection was marginally significant (p=0.067), while a history of IDU, ethnicity, gender, age at diagnosis, and year of diagnosis were not. Among the seroconversion cohort, no predictors of progression to immunological AIDS were identified. Ethnicity, hepatitis C coinfection and history of IDU could not be assessed. Conclusion: Our study found that IDU, HCV coinfections, baseline CD4 counts, and ART use were significant predictors of disease progression. This highlights the need for increased testing and early detection and for targeted interventions for these particularly vulnerable populations to slow disease progression.
356

Switching Focus in New Business Enterprise:From a Survival to a Profit Orientation

Ramezani Tehrani, Bahareh January 2009 (has links)
What objective should an entrepreneur focus on when starting a new business enterprise? Both a survival orientation and a profit one are important for the continuity of the new venture, but a survival focus is key in the hazardous early months or even years. In this thesis, I identify the conditions under which an entrepreneur should switch from a survival orientation, where the venture’s likelihood of survival is more critical, to a profit orientation where the venture’s profit instead is more critical. I accomplish this task by determining the optimal time to switch from a survival to a profit orientation based on maximizing the entrepreneur’s accumulated utility over a given time horizon. At each time period, the utility is positively associated with the amount of added value to the business venture that entrepreneur owns and manages, and the time horizon is determined by the time at which the entrepreneur’s venture exit – for instance, it is being sold. That added value contains a planned portion (e.g., due to what the entrepreneur can control) and an unplanned portion. The portion of a firm’s added value that is unplanned depends on the entrepreneur’s orientation, whereby, at any time period, the expected added value and its variation are considered to be low under a survival orientation, but they are considered to be high under a profit orientation. I use an approach from the economics literature, known as the LEN model, where the use of an exponential utility function (E), a linear relationship between the utility and random effects (L), and normality of those random effects (N) allow me to transfer the probabilistic objective function into a certainty equivalent that makes the problem tractable. The decision framework and its resulting findings suggest two environmental and two entrepreneurial characteristics that influence the existence of a time at which to switch orientation from survival to profit. Based on these characteristics, I derive sixteen scenarios and discussed some of the necessary conditions for the existence of a switching time. I find that it is not straightforward to determine whether the orientation switch should be delayed or expedited as business environments (or entrepreneurial types) are compared. I thus further develop my analysis by adding more structure to the functional forms that underline the behavior of how the mean of and variation in the firm’s added value are regulated over time, as well as for the risk propensity of the firm’s owner. This exercise allow me to study the conditions under which the switching time should be delayed or expedited, and to numerically investigate the behavior of a firm’s total valuation as changes occur in key model parameters. I use franchising as an application of the sensitivity analysis I perform to identify whether a change in a model parameter (everything else being equal) should delay or expedite the orientation switch. Based on this application, I would advise entrepreneurs to switch their orientation later if they go into entrepreneurship as a franchisee rather than as a franchisor. A simulation analysis allows me to further propose a positive relationship between a firm’s total valuation and the planned added value by the entrepreneur to that firm. That analysis also suggests a positive relationship between a firm’s total valuation and the expected unplanned-added-value growth under a profit orientation, but a negative relationship under a survival orientation. Further, I find a positive relationship between total valuation and the variation in unplanned-added-value growth under a survival orientation, but a negative relationship under a profit orientation. One of the key challenges that have been raised for future entrepreneurship research is how to define an entrepreneur’s objective function. My thesis contributes to this debate by suggesting that, in the early years, there should be an orientation switch, that is, sequentially as opposed to simultaneously consider both survival and profit maximization. My thesis also contributes to the literature on firm growth because using risk-return tradeoffs to characterize the two orientations is unique in the entrepreneurial context, and so is the consideration of a sequential use of these orientations to study firm added value over time and the resulting accumulated total valuation. Characterizing each of the two orientations – survival and profit – based on risk-return tradeoffs and linking these orientations to firm growth open up new avenues for research in entrepreneurial decision making.
357

Survival and Inactivation of Bacteriophage Φ6 on N95 Respirator Material

Waka, Betelhem 20 December 2012 (has links)
Introduction: Preventing healthcare professionals from acquiring occupational infectious diseases is very important in maintaining healthcare delivery systems. For protection in the work place, healthcare professionals use PPE which helps prevent exposure to pathogens during patient care. N95 respirators protect healthcare workers against airborne pathogens that are known to be associated with different respiratory diseases. Since previous studies have shown that viruses can survive on PPE surfaces, it is important to examine the survival of viruses on respirators to determine if reuse of the same N95 respirator is possible when PPE shortages occur. Goal: The goal of this research is to determine the inactivation of bacteriophage Φ6 on the surface of N95 respirators at ambient temperature and two different relative humidity levels, 40 and 60%. Result: The linear regression showed that rate of inactivation was much lower in 40% than 60% RH (40%: Slope= -0.046± 0.007040; 60%: Slope= -0.20± 0.006136). Over 24 hours, there was a ~1 Log10 reduction in virus at 20°C and 40% RH, while there was a ~4 Log10 reduction at 20°C and 60% RH. Within the timeframe of a single patient encounter, there was a <0.02 Log10 reduction in virus at 40% RH and a <0.1 Log10 reduction at 60% RH. Conclusion: Bacteriophage Φ6 survives on N95 respirators for up to 24 hours at ambient temperature and 40 and 60% relative humidity levels. Inactivation rate was lower in 40% than 60% RH. The results showed that enveloped viruses survive on the surface of N95 respirators for longer than a single patient encounter. Therefore, this should be taken into consideration when doing a risk assessment of reusing N95 respirators when shortages occur.
358

Skräckens ansikte : en studie i skräckgenrens historia och inflytande för visualiseringen av spelkaraktärer

Tidlund, Jonas January 2010 (has links)
Hur utformas spelkaraktärer för att förmedla skräck till betraktaren?  Spelkaraktärer inom survival-horrorgenren har flera konventioner baserade på skräckgenrens tidigare historia. Både kvinnliga och manliga karaktärer har tydligt fokus på sexualisering. Kropp och klädsel används för att markera avstånd från betraktarens kultur. Färger som betonar sexualitet, våld och ondska återkommer i karaktärernas utformning. Ljus och klädsel används även för att begränsa betraktarens information om karaktären. 2 karaktärer har producerats, en av vardera kön. Dessa används till en enkätundersökning för att testa relationen mellan vana av skräckgenren, hur skräckinjagande de uppfattas samt hur sexualiserade de anses. Resultaten av undersökningen är att det mest avgörande för att skapa skräckinjagande karaktärer var att de betraktas som fysiskt farliga och att karaktären inte är en del av betraktarens kultur. Relationen mellan skräck och kultur kan vidareutvecklas i framtida arbete inom krigs- och propagandaaffischer relevant. Skräckgenren och propaganda är något som tycks innehålla flera likheter.
359

Duration Data Analysis in Longitudinal Survey

Boudreau, Christian January 2003 (has links)
Considerable amounts of event history data are collected through longitudinal surveys. These surveys have many particularities or features that are the results of the dynamic nature of the population under study and of the fact that data collected through longitudinal surveys involve the use of complex survey designs, with clustering and stratification. These particularities include: attrition, seam-effect, censoring, left-truncation and complications in the variance estimation due to the use of complex survey designs. This thesis focuses on the last two points. Statistical methods based on the stratified Cox proportional hazards model that account for intra-cluster dependence, when the sampling design is uninformative, are proposed. This is achieved using the theory of estimating equations in conjunction with empirical process theory. Issues concerning analytic inference from survey data and the use of weighted versus unweighted procedures are also discussed. The proposed methodology is applied to data from the U. S. Survey of Income and Program Participation (SIPP) and data from the Canadian Survey of Labour and Income Dynamics (SLID). Finally, different statistical methods for handling left-truncated sojourns are explored and compared. These include the conditional partial likelihood and other methods, based on the Exponential or the Weibull distributions.
360

Switching Focus in New Business Enterprise:From a Survival to a Profit Orientation

Ramezani Tehrani, Bahareh January 2009 (has links)
What objective should an entrepreneur focus on when starting a new business enterprise? Both a survival orientation and a profit one are important for the continuity of the new venture, but a survival focus is key in the hazardous early months or even years. In this thesis, I identify the conditions under which an entrepreneur should switch from a survival orientation, where the venture’s likelihood of survival is more critical, to a profit orientation where the venture’s profit instead is more critical. I accomplish this task by determining the optimal time to switch from a survival to a profit orientation based on maximizing the entrepreneur’s accumulated utility over a given time horizon. At each time period, the utility is positively associated with the amount of added value to the business venture that entrepreneur owns and manages, and the time horizon is determined by the time at which the entrepreneur’s venture exit – for instance, it is being sold. That added value contains a planned portion (e.g., due to what the entrepreneur can control) and an unplanned portion. The portion of a firm’s added value that is unplanned depends on the entrepreneur’s orientation, whereby, at any time period, the expected added value and its variation are considered to be low under a survival orientation, but they are considered to be high under a profit orientation. I use an approach from the economics literature, known as the LEN model, where the use of an exponential utility function (E), a linear relationship between the utility and random effects (L), and normality of those random effects (N) allow me to transfer the probabilistic objective function into a certainty equivalent that makes the problem tractable. The decision framework and its resulting findings suggest two environmental and two entrepreneurial characteristics that influence the existence of a time at which to switch orientation from survival to profit. Based on these characteristics, I derive sixteen scenarios and discussed some of the necessary conditions for the existence of a switching time. I find that it is not straightforward to determine whether the orientation switch should be delayed or expedited as business environments (or entrepreneurial types) are compared. I thus further develop my analysis by adding more structure to the functional forms that underline the behavior of how the mean of and variation in the firm’s added value are regulated over time, as well as for the risk propensity of the firm’s owner. This exercise allow me to study the conditions under which the switching time should be delayed or expedited, and to numerically investigate the behavior of a firm’s total valuation as changes occur in key model parameters. I use franchising as an application of the sensitivity analysis I perform to identify whether a change in a model parameter (everything else being equal) should delay or expedite the orientation switch. Based on this application, I would advise entrepreneurs to switch their orientation later if they go into entrepreneurship as a franchisee rather than as a franchisor. A simulation analysis allows me to further propose a positive relationship between a firm’s total valuation and the planned added value by the entrepreneur to that firm. That analysis also suggests a positive relationship between a firm’s total valuation and the expected unplanned-added-value growth under a profit orientation, but a negative relationship under a survival orientation. Further, I find a positive relationship between total valuation and the variation in unplanned-added-value growth under a survival orientation, but a negative relationship under a profit orientation. One of the key challenges that have been raised for future entrepreneurship research is how to define an entrepreneur’s objective function. My thesis contributes to this debate by suggesting that, in the early years, there should be an orientation switch, that is, sequentially as opposed to simultaneously consider both survival and profit maximization. My thesis also contributes to the literature on firm growth because using risk-return tradeoffs to characterize the two orientations is unique in the entrepreneurial context, and so is the consideration of a sequential use of these orientations to study firm added value over time and the resulting accumulated total valuation. Characterizing each of the two orientations – survival and profit – based on risk-return tradeoffs and linking these orientations to firm growth open up new avenues for research in entrepreneurial decision making.

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