Doctor of Philosophy

dissertationThis document includes three papers from my research on residence among the Twe people of the Lower Kunene Region. The first paper gives an ethnographic account of the Twe. I discuss the Twe's mysterious and potentially unique ethnic history, their complex subsistence, and the ways in which their social organization differs from that of neighboring tribes. The second paper presents a simulation model that shows how we might expect the role of secondary childcare provider to shift from a woman's mother to her older daughters as she moves through her reproductive career. This dynamic might explain why women would want to remain in their natal camp until later in life. This is a common pattern among many traditional populations that is particularly relevant to the study of hunter-gatherers and other groups with limited heritable wealth. The final paper offers an empirical test of the relationship between childcare assistance and residence. Using genealogical and residence history data, I investigate whether women with young dependent children are more likely to live with their mothers. I also test whether women move away from home when they have babysitting daughters as predicted in the preceding simulation model. The findings in the third paper are consistent with both of these expectations

Habitat Selection and Sexual Suggestion of Rocky Mountain Bighorn Sheep in Custer State Park, South Dakota

Spatial segregation between Rocky Mountain bighorn sheep (Ovis canadensis canadensis) ram and ewe herds has been documented by Geist (1971), Geist and Petocz (1977), Shank (1979), Morgantini and Hudson (1981), and Hogg (1983), where ram herds consist of mature males approximately 4 years old and older and ewe herds are comprised of all other individuals. Geist (1971), Shank (1979), and Hogg (1983) have shown that segregation occurs year-round except during the breeding season (November and December) when the sexes congregate on a traditional breeding range (cf. Geist 1971, p 209). These studies also have shown that the sexes remain separated during the winter, when segregation should be least likely. During winter, resources, particularly forage, are most limiting and when the sexes would be expected to remain congregated after the breeding season, such as at available foraging sites. However, both Geist and Petocz (1977) and Morgantini and Hudson (1981) reported that the sexes remained segregated on a continuous winter range, even during severe winters. Four hypotheses have been developed to explain sexual segregation of bighorn sheep. Shank (1979) believed sexual segregation was a result of differential habitat requirements due to sexual dimorphism. Segregation has been suggested as an anti-predator strategy for males which are physically weakened after the breeding season (Geist and Bromely 1978). Morgantini and Hudson (1981) suggested that sexual segregation reduces frequency of agonistic interactions among rams during the post-breeding season and maximizes fitness of rams by conserving energy when reproduction is not possible. Geist and Petocz (1977) explained segregation as a mechanism for rams to minimize habitat competition with pregnant ewes and their prospective lambs, thus increasing survival of lambs, and thereby maximizing reproductive fitness of rams

STOCHASTIC WEALTH DYNAMICS AND RISK MANAGEMENT AMONG A POOR POPULATION

The literature on economic growth and development has focused considerable attention on questions of risk management and the possibility of multiple equilibria associated with poverty traps. We use herd history data collected among pastoralists in southern Ethiopia to study stochastic wealth dynamics among a very poor population. These data yield several novel findings. Although covariate rainfall shocks plainly matter, household-specific factors, including own herd size, account for most observed variability in wealth dynamics. Despite longstanding conventional wisdom about common property grazing lands, we find no statistical support for the tragedy of the commons hypothesis. It appears that past studies may have conflated costly self-insurance with stocking rate externalities. Such self-insurance is important in this setting because weak livestock markets and meager social insurance cause wealth to fluctuate largely in response to biophysical shocks. These shocks move households between multiple dynamic wealth equilibria toward which households converge following nonconvex path dynamics. The lowest equilibrium is consistent with the notion of a poverty trap. These findings have broad implications for the design of development and relief strategies among a poor population extraordinarily vulnerable to climatic shocks.common property, covariate risk, Ethiopia, idiosyncratic risk, poverty traps, social insurance, Risk and Uncertainty, O1, Q12,

Optimization by nonhierarchical asynchronous decomposition

Large scale optimization problems are tractable only if they are somehow decomposed. Hierarchical decompositions are inappropriate for some types of problems and do not parallelize well. Sobieszczanski-Sobieski has proposed a nonhierarchical decomposition strategy for nonlinear constrained optimization that is naturally parallel. Despite some successes on engineering problems, the algorithm as originally proposed fails on simple two dimensional quadratic programs. The algorithm is carefully analyzed for quadratic programs, and a number of modifications are suggested to improve its robustness

At the Start of the Sarcomere: A Previously Unrecognized Role for Myosin Chaperones and Associated Proteins during Early Myofibrillogenesis

The development of striated muscle in vertebrates requires the assembly of contractile myofibrils, consisting of highly ordered bundles of protein filaments. Myofibril formation occurs by the stepwise addition of complex proteins, a process that is mediated by a variety of molecular chaperones and quality control factors. Most notably, myosin of the thick filament requires specialized chaperone activity during late myofibrillogenesis, including that of Hsp90 and its cofactor, Unc45b. Unc45b has been proposed to act exclusively as an adaptor molecule, stabilizing interactions between Hsp90 and myosin; however, recent discoveries in zebrafish and C. elegans suggest the possibility of an earlier role for Unc45b during myofibrillogenesis. This role may involve functional control of nonmuscle myosins during the earliest stages of myogenesis, when premyofibril scaffolds are first formed from dynamic cytoskeletal actin. This paper will outline several lines of evidence that converge to build a model for Unc45b activity during early myofibrillogenesis

Automatic Tail-Cutter

Essity commissioned Olivet Senior Design Team #9 with the creation of a device that will expedite the roll change time on Machine #515 while maintaining the safety standards that Essity has set forth. The current process is manual, with inefficiencies due to operators entering and leaving the machine area along with a slow manual cut time. Our goal is to optimize this process with the addition of a new process and/or devices. The solution provided to Essity was the addition of a lowering device and a cutting device which were to be used alongside an existing piece of equipment on Machine #515

Toward Parallel Mathematical Software for Elliptic Partial Differential Equations

Three approaches to parallelizing important components of the mathematical software package ELLPACK are considered: an explicit approach using compiler directives available only on the target machine, an automatic approach using an optimizing and parallelizing precompiler, and a two-level approach based on extensive use of a set of low level computational kernels. The focus is on shared memory architectures. Each approach to parallelization is described in detail, along with a discussion of the effort involved. Performance on a test problem, using up to sixteen processors of a Sequent Symmetry S81, is reported and discussed. Implications for the parallelization of a broad class of mathematical software are drawn