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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.
221

Distinct cachexia phenotypes and the importance of adipose tissue loss on survival of patients with advanced pancreatic cancer on FOLFIRINOX chemotherapy

Kays, Joshua 12 1900 (has links)
Indianapolis / By the traditional definition of unintended weight loss, cachexia develops in ~80% of patients with pancreatic ductal adenocarcinoma (PDAC). Here we measure the longitudinal body composition changes in patients with advanced PDAC undergoing FOLFIRINOX therapy. We performed a retrospective review of 53 patients with advanced PDAC on FOLFIRINOX as first line therapy at Indiana University Hospital from July 2010 to August 2015. Demographic, clinical, and survival data were collected. Body composition measurement, trend, univariate and multivariate analysis were performed. Three cachexia phenotypes were identified. The majority of patients, 64%, had Muscle-and-Fat Wasting (MFW), while 17% had Fat-Only Wasting (FW) and 19% had No Wasting (NW). NW had significantly improved overall median survival (OMS) of 22.6 months vs. 13.0 months for FW and 12.2 months for MFW (p=0.02). FW (HR=5.2; 95%CI=1.5-17.3) and MFW (HR=1.8; 95%CI=1.1-2.9) were associated with an increased risk of mortality compared to NW. OMS and risk of mortality did not differ between FW and MFW. Progression of disease, sarcopenic obesity at diagnosis, and primary tail tumors were also associated with decreased OMS. On multivariate analysis cachexia phenotype and chemotherapy response were independently associated with survival. Three phenotypes of cachexia were observed. Moreover, three phenotypes suggests molecular or genetic heterogeneity of host or tumor. Identifying these differences will be vital to defining optimal treatment for cachexia. Survival among FW was as poor as MFW suggesting adipose tissue plays a crucial role in cachexia. Blunting or possibly preventing cachexia may confer a significant survival advantage in patients with advanced PDAC.
222

Joint modeling of longitudinal and survival outcomes using generalized estimating equations

Zheng, Mengjie 07 May 2018 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Joint models for longitudinal and time-to-event data has been introduced to study the association between repeatedly measured exposures and the risk of an event. The use of joint models allows a survival outcome to depend on some characteristic functions from the longitudinal measures. Current estimation methods include a two-stage approach, Bayesian and maximum likelihood estimation (MLEs) methods. The twostage method is computationally straightforward but often yields biased estimates. Bayesian and MLE methods rely on the joint likelihood of longitudinal and survival outcomes and can be computationally intensive. In this work, we propose a joint generalized estimating equation framework using an inverse intensity weighting approach for parameter estimation from joint models. The proposed method can be used to longitudinal outcomes from the exponential family of distributions and is computationally e cient. The performance of the proposed method is evaluated in simulation studies. The proposed method is used in an aging cohort to determine the relationship between longitudinal biomarkers and the risk of coronary artery disease.
223

Survival Analysis for the Association between Anti-hypertensive Medication and Time to Dementia with Competing Risk

Hu, Xinhua Flora 06 1900 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Background: High blood pressure (HBP) is a common risk factor for dementia in elder population. Anti-hypertensive medications have been reported to associate with lower incidence rate of dementia in elder African Americans. The Apolipoprotein E (ApoE) epsilon 4 allele has been shown to be associated with both increased dementia and hypertension risk. However, previous studies had not examined the association between anti-hypertensive medications by ApoE status accounting for the competing risk from death. Methods: This is a prospective observational cohort study in 1236 community-dwelling hypertensive African Americans aged 65 years and older without dementia at baseline, with follow-up cognitive assessment and clinical evaluation for dementia diagnosis. Dementia-free mortality was considered as the competing risk. Of these, 707 participants were genotyped for ApoE status. Anti-hypertensive medication use was obtained from prescription records in the electronic medical records of the Indiana Network for Patient Care (INPC). Cox proportional cause-specific hazard (CSH) regression models were applied to assess the association between anti-hypertensive medication use and CSHs for dementia and death in ApoE epsilon 4 carriers and non-carriers separately. Key results: In ApoE epsilon 4 carriers, participants using anti-hypertensive medications had lower CSH of dementia compared to those not on anti-hypertensive medications before adjusting for blood pressure (BP) (hazard ratio (HR), 0.365; 95% CI, 0.170 – 0.785; p = 0.0099). The HR was no longer significant once BP control was adjusted (HR, 0.784; 95% CI, 0.197 – 3.123; p = 0.7303). Anti-hypertensive medications were not associated with dementia rate in non-carriers. In ApoE epsilon 4 non-carriers, participants on anti-hypertensive treatment showed significantly lower CSH of death compared to those not on mediations adjusting for covariates and BP control (HR, 0.237; 95% CI, 0.149 – 0.375; p < 0.0001). There was no significant association between anti-hypertensive medication use and death in ApoE epsilon 4 carriers. Conclusions: Anti-hypertensive medication was associated with lower dementia rate in ApoE epsilon 4 carriers and that rate was primarily mediated through BP control. In non-carriers, anti-hypertensive medication was significantly associated with lower mortality rate and this association appears to be independent of BP control.
224

Survival and Growth Performance of Two Oak Species and Three Planting Stocks on Lands Disturbed by Hurricane Katrina

Dowdy, Andrew Dees 09 May 2015 (has links)
Survival and growth of two oak species, water oak (Quercus nigra) and swamp chestnut oak (Quercus michauxii), and three planting stocks: 1-0 bareroot, conventional containerized, and EKOgrownTM seedlings were compared for two growing seasons. Conventional containerized seedlings had the best survival. Bareroot seedlings had the second highest survival and EKOTM seedlings had the lowest at the end of two growing seasons. Conventional containerized planting stock exhibited greater groundline diameter (GLD) growth for both species at the end of the first growing season compared to bareroot and EKOTM planting stock. Bareroot seedlings had similar GLD growth to EKOTM seedlings for both years. Conventional containerized seedlings height differed in water oak but did not differ in swamp chestnut oak at the end of year two compared to bareroot seedlings. EKOTM seedlings exhibited severe dieback at the end of both growing seasons and the least amount of height growth.
225

Lessons for Thriving on the Tenure Track: Survival Tips From Assistant and Tenured Professors

Case, Kim A., Williams, Jeannetta, Williams, Stacey L., Shelton, Nicole 01 June 2008 (has links)
This discussion begins with an introduction by faculty presenters currently on the journey toward tenure and those recently tenured. The panelists intend to cover topics including tips for surviving the first year, finding time for research, planning and preparing for your tenure review, and managing balance. How might faculty carve out the necessary time to cultivate an active research program, especially at teaching institutions? What materials should faculty collect for presentation in their tenure case file? How might faculty manage success in various professional expectations with regard to research, teaching, and service? How might faculty deal with the potential pitfalls of departmental and institutional politics? Ideas, experiences, and questions from discussion attendees are more than welcome.
226

Trapping, Survival, and Probable Causes of Mortality of Chukar Partridge

Robinson, Aaron Clark 29 November 2007 (has links) (PDF)
We present an efficient and effective method for trapping chukars (Alectoris chukar) on artificial water sources. We compared a B-trap, a prairie chicken (Tympanuchus cupido) walk-in trap, a modified quail recall trap, and a newly designed Utah walk-in-funnel trap. Our Utah funnel trap outperformed standard techniques by more than 65%, and exceeded previous published results by 35%. Use of this method allows researchers and managers the ability to capture large numbers of Chukars relatively efficiently. With appropriate modifications this design is applicable for capturing a variety of bird species using small water developments. Chukars (Alectoris chukar) have been introduced throughout the world. Limited information regarding seasonal survival, causes of mortality, and other basic life history characteristics such as movements, home range, nesting and brood ecology, are available throughout their historical and introduced range of distribution. Lack of information is surprising because chukars have been introduced throughout the world and are popular with sport hunters. Survival estimates are particularly important for understanding population fluctuations which allows for adequate management. We evaluated the relationship of fall raptor migration, peak migration, reproductive period, and year effects on survival of chukars at 5 sites in western Utah. We also evaluated the probable cause of death for chukars with transmitters attached by examining evidence at kill sites. We captured and fitted 128 chukars with two different sized radio transmitters (99 females, 21 males, 8 sexes undetermined). Survival differed among study years where survival estimates showed significant (P< 0.01) differences between estimates in 2005 (Ψ = 0.03, 95% CI = 0.01 - 0.09), compared to 2006 (Ψ = 0.26, 95% CI = 0.18 - 0.38). Estimates showed that chukars were less likely to survive (P = 0.01) during the fall peak of raptor migration in 2006 (bi-monthly Ψ = 0.86, 95% CI = 0.74 - 0.93) than (base survival) outside this migration period and during the chukar reproductive period (bi-monthly Ψ = 0.97, 95% CI = 0.95 - 0.98). We documented 95 deaths; with 45% of causes unknown, avian predation accounted for 30%, mammals killed 1%, and hunters accounted for 7.6%. Our research suggested that predation on chukars was substantial during the fall raptor migratory period.
227

Effective exposure: lag-parameterized exponential models for exposure risk

Gerlovin, Hanna 13 November 2018 (has links)
Many observational studies assessing the effects of treatments or exposures are limited to comparisons between treatment users and nonusers or exposed and unexposed participants at study entry. However, the underlying and etiologically relevant exposure may gradually increase over time before reaching some plateau. This amount of time required for this latent cumulative exposure to reach a maximum hazard will be referred to as the "lag", coming from the concept that the association between exposure and outcome is lagged or delayed. Accounting for the lag is essential when analyzing exposure-response associations adequately. My challenge was to simultaneously estimate the lag-time and the exposure's lagged-association with the outcome at plateau. In this dissertation, I draw an analogy with the pharmacokinetic one-compartment model (OCM). OCM describes the accumulation of a medication in the body based on an exponential cumulative density function whose rate of increase is defined by a half-life parameter. Upon discontinuation, the OCM assumes that a medication will eliminate at the same half-life rate. The decline, for my purposes, can be interpreted as the time to return to a null effect of exposure, which occurs at roughly 4-5 half-lives. My methods model the association of a latent exposure and dichotomous outcome using a half-life of effect, similar to the OCM, in longitudinal analyses of single and repeated exposures. I derive profile likelihood-based algorithms to estimate of the upper limit of association simultaneously with the rate of latent exposure growth towards or away from plateau. Lastly, I extend this approach to allow different half-life parameters for incline and decline. Using simulations, I analyze the performance of my approach by comparing bias and coverage of the estimates for the half-life and effect parameters. With data from the Black Women's Health Study Cohort (a prospective cohort of 59,000 women followed 1995-2015), I show that prolonged cigarette smoking is associated with a maximum hazard of cardiovascular disease (CVD) at 2.5 times the hazard of never smokers. Additionally, I estimate that it takes about 7 years of smoking cessation for an individual's hazard of CVD to decrease by 50%. / 2020-11-13T00:00:00Z
228

Population Forecasting for the Town of Ancaster

Allemang, Mark January 1986 (has links)
<p> This paper applies a cohort survival model to an age-and sex-disagqregated 1985 'base' population of Ancaster. Using a fortran programme, low, high, and 'most probable' projections were made for a 1986 to 2001 time horizon. The migration component was found to be the single most important projection variable. Consequently, only migration was varied between the three sets of projections. In analyzing migration for Ancaster, we identified a persistent trend in net migration over the 1971 to 1985 period. This finding allowed us to apply the 1985 male and female age profiles of net migration to the in-migrants. Thus, this study more accurately quantified net Migration than previous studies. </p> / Thesis / Bachelor of Arts (BA)
229

Axenic Culture of House-Fly Larvae and the Influence of Stored Nutrients on Adult Dietary Requirements for Survival and Reproduction

Taylor, Grace Catherine 05 1900 (has links)
Larvae of the house fly, Musca domestica L. , were reared axenically on semi-synthetic media and their performance both as larvae and as adults was assessed in comparison to that of flies reared on an undefined wheat-bran medium. Three components of a standard sterile casein-base medium, i.e., sodium oleate, RNA and cholesterol, were assessed as to their effects on both the larval and adult stages. All improved larval growth, with cholesterol being essential. It has been substantiated that specific larval nutrient reserves were transferred to the adult. Larval nutrition influenced fecundity through its effect on adult survival and vigour, number of eggs developed, and the adult hormonal system. / Thesis / Master of Science (MSc)
230

Functional Data Analysis and its application to cancer data

Martinenko, Evgeny 01 January 2014 (has links)
The objective of the current work is to develop novel procedures for the analysis of functional data and apply them for investigation of gender disparity in survival of lung cancer patients. In particular, we use the time-dependent Cox proportional hazards model where the clinical information is incorporated via time-independent covariates, and the current age is modeled using its expansion over wavelet basis functions. We developed computer algorithms and applied them to the data set which is derived from Florida Cancer Data depository data set (all personal information which allows to identify patients was eliminated). We also studied the problem of estimation of a continuous matrix-variate function of low rank. We have constructed an estimator of such function using its basis expansion and subsequent solution of an optimization problem with the Schattennorm penalty. We derive an oracle inequality for the constructed estimator, study its properties via simulations and apply the procedure to analysis of Dynamic Contrast medical imaging data.

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