No description available.

No description available.

The relationship among oxidative stress, mitochondrial DNA integrity, and longevity continues to be without a general consensus. Here, we hypothesize that short- and long-lived birds, including the budgerigar (Melopsittacus undulatus), guineafowl (Numida meleagris), quail (Corturnix japonica), and turkey (Meleagris gallopavo) differ in oxidative stress measured by blood markers and that this difference correlates with mitochondrial genomic integrity both within and among species. In preliminary studies and to establish a reference and standard for the search for single nucleotide polymorphisms (SNPs), we used a combination of experimental and in silico tools for genome analysis to screen selected regions of the chicken (Gallus gallus) mitochondrial genome (mtGenome) for SNPs. A total of 113 SNPs was identified which formed 17 haplotypes. The length of the turkey mtGenome sequence developed was 16,967 bp in length, while that of the budgie was 18,193 bp. Annotation of both sequences revealed a total of 13 genes and 24 RNA (22 tRNA and 2 rRNA). Within the budgie mtGenome sequence, a duplicated control region was observed, and there was an additional nucleotide in the NADH dehydrogenase subunit 3 sequence of both the turkey and budgie. The total number of SNPs within the D-loop and 16S rRNA in each of the four species ranged from zero in the quail to 22 in the budgie. The new mtGenome sequences revealed that the turkey was most closely related to the chicken and quail, and the budgie was closest to kakabo (Strigops habroptilus). Oxidative stress, estimated by biomarkers thiobarbiturate acid reacting substance (TBARS), plasma uric acid (PUA), and glutathione (GSH) and at 10, 30, 55, and 80 wks-of-age within each species, was not consistent. The level of GSH was highest in guineafowl, but lowest in budgie. While PUA, an antioxidant, exhibited a significantly (P<0.05) decrease as birds grew order, TBARS, a lipid peroxidation index, increased with age. In general, oxidant and antioxidant status appeared to vary among species and to be significantly affected by age, unlike mutations in the mtDNA which remained the same in younger and older birds. This primary findings and discoveries of this dissertation research include the large scale SNP discovery in previously described and novel avian mtGenomes including the chicken and turkey, the two main poultry species, and the determination that oxidative stress in birds appears to vary with age but that this does not affect mitochondrial DNA variation. Recent evidence of work in mice appears to support results described in this dissertation that mitochondrial DNA mutations do not increase with age, the central paradigm of the "Free Radical Theory of Aging". The dissertation also described resources and data that will be a foundation for the use of birds, especially the budgie, as a model for testing this theory that remains of interest to both agricultural and biomedical sciences. / Ph. D.

Identifying appropriate international distributors for small and medium-sized enterprises (SMEs) in the software industry for overseas markets can determine a firm's future endeavors in international expansion. SMEs lack the complex skills in market research and decision analysis to identify suitable partners to engage in global market entry. Foreign distributors hold responsibility to represent, sell, market, and add value to the software manufacturer's products in local markets. Identifying appropriate attributes to determine a suitable distributor is essential in assuring success in new export markets. Methods for partner selection have been addressed in the international marketing and information systems literature. Building on this literature, this dissertation develops an improved method for identifying suitable distributors in the SME software industry. The partner selection conundrum is modeled as a binary classification problem in that it involves predicting whether an alliance relationship will survive over a specific period. The challenge presented to researchers is not just the large number of variables involved in the selection process but also the inherent uncertainty in the decision making process. This study uses a Bayesian methodology for this classification task. A Naïve Bayes (NB) classification model was developed factoring sixteen alliance attributes identified in the partner selection literature and validated by domain experts who scored the importance of these attributes. Thirty years of partnership data that contributed to relationship longevity trained the model and held-back data was used to validate the model. The NB classification model returned accurate predictions in both the group of foreign distributors that succeeded and failed to reach the relationship longevity threshold of five years. The study's contribution to the software SME business community and its practitioners was the identification of an improved methodology for predictive success. The approach employed a simple Bayesian prediction model utilizing key alliance attributes to help software SMEs identify potential foreign distributor partners who can sustain relationship longevity from which to build a strong business partnership. Keeping the methodology simple is critical for SMEs who struggle with an abundance of challenges to maintain their corporate viability in the market place.

Thesis MSc(Agric)--Stellenbosch University, 1973. / ENGLISH ABSTRACT: no abstract available / AFRIKAANSE OPSOMMING: geen opsomming

Although largely overlooked in much of the previous research on political tolerance, I argue that contextual factors, specifically state-level features, play a significant role in influencing individual tolerance judgments. Drawing from extant theories of public opinion, international conflict, and political institutions, I seek to further our understanding of the determinants of political tolerance by trying to answer the following question: What accounts for the significant differences in political tolerance levels across countries? While models using individual-level predictors account for some of the disparity in tolerance levels, a substantial amount remains unexplained. I assert that several macro-level theoretical frameworks offer compelling explanations for the marked difference in tolerance levels across countries. Specifically, I examine the effect of state-level external threats, internal threats, and the role of domestic political institutions in shaping individual attitudes towards unpopular groups. To test my propositions, I use data from the 1995-1997 World Values survey as well as multi-level statistical modeling to estimate the aggregate effects of state-level factors on political tolerance levels across 33 countries while also controlling for individual-level predictors.This dissertation demonstrates that elevated objective threats to the state, whether international disputes or incidents of civil conflict, serve to dampen overall tolerance levels. In doing so, this study also highlights that not all types of external threat resonateequally amongst the public. Individuals in countries involved in territorial disputes or countries targeted in international disputes are generally less tolerant overall than those in countries involved in disputes over other issues. In terms of domestic political institutions, I find that electoral rules designed to build consensus and ameliorate societal tensions among groups may actually serve to foster intolerance in countries under certain conditions. Finally, my analyses reveal that the effect of democratic longevity on political tolerance levels is actually conditional based on the type of political institutions that exist in a country. Overall, the findings discovered here underscore the importance of contextual factors in shaping political tolerance levels across countries and stresses the need for this type of analysis in future studies of political tolerance.

This dissertation studies the adverse financial implications of "longevity risk" and "mortality risk", which have attracted the growing attention of insurance companies, annuity providers, pension funds, public policy decision-makers, and investment banks. Securitization of longevity/mortality risk provides insurers and pension funds an effective, low-cost approach to transferring the longevity/mortality risk from their balance sheets to capital markets. The modeling and forecasting of the mortality rate is the key point in pricing mortality-linked securities that facilitates the emergence of liquid markets. First, this dissertation introduces the discrete models proposed in previous literature. The models include: the Lee-Carter Model, the Renshaw Haberman Model, The Currie Model, the Cairns-Blake-Dowd (CBD) Model, the Cox-Lin-Wang (CLW) Model and the Chen-Cox Model. The different models have captured different features of the historical mortality time series and each one has their own advantages. Second, this dissertation introduces a stochastic diffusion model with a double exponential jump diffusion (DEJD) process for mortality time-series and is the first to capture both asymmetric jump features and cohort effect as the underlying reasons for the mortality trends. The DEJD model has the advantage of easy calibration and mathematical tractability. The form of the DEJD model is neat, concise and practical. The DEJD model fits the actual data better than previous stochastic models with or without jumps. To apply the model, the implied risk premium is calculated based on the Swiss Re mortality bond price. The DEJD model is the first to provide a closed-form solution to price the q-forward, which is the standard financial derivative product contingent on the LifeMetrics index for hedging longevity or mortality risk. Finally, the DEJD model is applied in modeling and pricing of life settlement products. A life settlement is a financial transaction in which the owner of a life insurance policy sells an unneeded policy to a third party for more than its cash value and less than its face value. The value of the life settlement product is the expected discounted value of the benefit discounted from the time of death. Since the discount function is convex, it follows by Jensen's Inequality that the expected value of the function of the discounted benefit till random time of death is always greater than the benefit discounted by the expected time of death. So, the pricing method based on only the life expectancy has the negative bias for pricing the life settlement products. I apply the DEJD mortality model using the Whole Life Time Distribution Dynamic Pricing (WLTDDP) method. The WLTDDP method generates a complete life table with the whole distribution of life times instead of using only the expected life time (life expectancy). When a life settlement underwriter's gives an expected life time for the insured, information theory can be used to adjust the DEJD mortality table to obtain a distribution that is consistent with the underwriter projected life expectancy that is as close as possible to the DEJD mortality model. The WLTDDP method, incorporating the underwriter information, provides a more accurate projection and evaluation for the life settlement products. Another advantage of WLTDDP is that it incorporates the effect of dynamic longevity risk changes by using an original life table generated from the DEJD mortality model table. / text

No description available.

This investigation studies the effects of diets containing varying amounts of linoleic acid (a polyunsaturated fatty acid) and stearic acid (a saturated fatty acid) on tumorigenesis, weight and longevity in strain A/ST mice. Linoleic acid [ 18 carbons and 2 double bonds (18:2)] was chosen to represent a fatty acid known to enhance tumorigenesis and obesity in certain strains of mice. Stearic acid [ 18 carbons and no double bonds (18:0)] represents a saturated fatty acid known to increase the latency period for mammary tumor development and to decrease the rate of tumor growth. This study was conducted to determine whether the effects of fatty acids observed in younger mice on time to tumor, survival and body weights were also found in aging animals. Further, by varying the amount of linoleic acid in the diet, this study examined whether the tumor enhancing effects of increasing amounts of linoleic acid could be overcome by the incorporation of dietary stearic acid. All diets had equal percentages, by weight, of protein, salt, sucrose, mineral salt, and vitamin levels and an equal number of calories per gram of food. The SF diet was rich in linoleic acid. The SA-1 diet contained enough linoleic acid to prevent essential fatty acid deficiency, and the SA-4 diet contained the maximal amount of linoleic acid for tumor enhancement. Total body weight and tumor production in the three dietary groups show a relationship between an increase in body weight and tumor production as the amount of dietary linoleic acid increases. There also is an inverse relationship between animal survival and body weight as the amount of dietary linoleic acid increases. Survival thus appears to be dependent on tumor production in the three dietary groups, where there appears to be an inverse relationship between survival and time to tumor as the amount of dietary linoleic acid increases at each timepoint. These results suggest that the inclusion of stearic acid in the diet can, in part, overcome this enhancing effect of linoleic acid, even at the optimal tumor producing level of linoleic acid. The results of this study indicate that that effects of linoleic and stearic acid in aging mice are similar to those in younger animals. / Department of Biology

In this qualitative study of middle school English teachers, I investigated the phenomenon of why teachers stay, year in and year out, despite challenges brought on by educational reforms and negative depictions from the general public. The teachers’ experiences illustrate the dedication and perseverance of professionals committed to working with students year in and year out. I framed this case study (Merriam, 1988) in theories of sensemaking (Maitliss & Christianson, 2014; Wieck, 1995) and critical pedagogy (Freire, 1970; Giroux, 2011). The participants were three teachers who taught middle school English for over ten years. Within this time frame, they were exposed to multiple, ongoing reforms: No Child Left Behind, Race to the Top, and Common Core State Standards. I used sensemaking and critical pedagogy lenses to explore how these teachers experienced issues of power and interpreted educational reforms. I also examined the reasons why they persisted in the profession. I employed grounded theory (Charmaz, 2006; Glaser & Strauss, 1967) and Gee’s (2011) Seven Building Tasks for analysis to identify four categories to illuminate the teachers’ stories: 1) Public Perception of the Profession, 2) Pedagogy and Curriculum, 3) Relationships, and 4) Being a Teacher. The teachers’ experienced ongoing struggles and yet had longevity in the profession. Implications of the study point to the perils and promises of long-term teaching. The perils were challenges of the profession: demands from administrators, new and limiting curriculum, a negative public perception, and long hours. The promises these teachers kept were commitments to decision makers and the public, middle school students and their families, and to the profession. It is these promises that they kept each year that motivated the teachers and sustained them over time.