A recent study on the Post-Formed properties of Superplastically Formed Magnesium AZ31B has shown that the heating time prior to testing has a major effect on the Post Forming properties of the superplastically material. To this point, there has been very little examination into the effect of pre-heating or annealing on superplastic forming (SPF) properties. In this work, the effects of annealing prior to the SPF of Mg AZ31 alloy were examined. Both high temperature SPF tensile and bulge specimens were formed after annealing. Multiple annealing temperatures were examined to produce specimens with grain sizes ranging from 8 andamp;igrave;m to 15 andamp;igrave;m for comparison with traditional SPF results. The results show that the effect of annealing can be suitable for the improvement of thinning and possibly the forming time of superplastically formed Magnesium alloys through the control of the microstructure.

The Panama Canal Watershed (PCW) represents a special opportunity for studies related to seed dormancy in the tropics with both applied and basic research objectives. There is a clear need for seed information for nursery planning in restoration projects that involves use of a large number of local species. Moreover, the strong rainfall gradient along the 60 km of continuous lowland forest in the PCW represents an excellent opportunity to understand dormancy and its role as an adaptive trait that evolved in response to environmental factors. This study presents useful seed information for 100 tree species native to the PCW. For each species, it includes collection system, fruiting time, seed mass, seed moisture content, germination, and longevity in storage at 20??C. For the first time, an attempt is made to classify (to class sensu Baskin andamp; Baskin 2004) the class of dormancy in seeds of the PCW. An analysis of the relationship between class of dormancy and seed mass, moisture content, longevity, germination patterns, and seasonality is presented. The relationship between class of seed dormancy and longevity and geographical distribution of species within the watershed based on the rainfall gradient was investigated.

Chronic disease is a major health burden in the United States, affecting about half of adults, and leading to poor health, disability, and death. However, the burden of chronic disease is not shared equally among Americans, with some groups (created by determinants such as race/ethnicity and socioeconomic resources) experiencing higher rates of morbidity and mortality. When measures of health and socioeconomic resources are examined together, a stepwise gradient pattern emerges. This social gradient has been established for individual measures, such as household income and social class, and several measures of morbidity and mortality. However, nationally, little research has been conducted using area-level measures, such as county economics, to examine its relationship with chronic disease. Three studies were completed using data from the Behavioral Risk Factor Surveillance System (BRFSS). County economic status was determined using unemployment, per capita market income, and poverty. The first study examined the relationship between county economic status and chronic disease and risk factors, both nationally and by metropolitan classification, using data from BRFSS 2013. Further, the social gradient was explored. The second study also used data from BRFSS 2013 to examine county economic status and prevalence of hypertension, arthritis, and poor health, after controlling for known risk factors. This study also examined results by US region. Finally, the third study assessed changes in disparities between persistently poor and persistently affluent counties for heart disease, hypertension, arthritis, and diabetes using data from BRFSS 2001-2010.

Regression models with correlated errors lead to nonadditivity of the information matrix. This makes the usual approach of design optimization (approximation with a continuous design, application of an equivalence theorem, numerical calculations by a gradient algorithm) impossible. A method is presented that allows the construction of a gradient algorithm by altering the information matrices through adding of supplementary noise. A heuristic is formulated to circumvent the nonconvexity problem and the method is applied to typical examples from the literature. (author's abstract) / Series: Forschungsberichte / Institut für Statistik

This project investigated the diagnosis and psychostimulant treatment rates of Attention Deficit/Hyperactivity Disorder (ADHD) in Manitoba children. These rates were considered according to sex, age, socioeconomic status (SES), geographical region, and comorbidity with learning disabilities (LD) and behavioral disturbances (BD). Data came from the Manitoba Population Health Research Data Repository, a comprehensive collection of administrative, registry, survey and other databases. The research population included all children aged 0 to 19 years in Manitoba (n = 319,506) with a diagnosis of ADHD (n= 9,233), during two Fiscal years (2003/2004 and 2004/2005). The term “gradient” refers to the relationship between SES and health and emphasizes the idea that the change in outcomes is gradual and occurs across the full range of SES. Results from this study indicate that region of residence (urban versus rural) and comorbid BD moderate the SES gradient, as low income, urban dwelling children with a comorbid diagnosis of BD had the highest rates of ADHD diagnoses and prescriptions. Furthermore, whereas age did not moderate the SES gradient, the crude rates indicated that the SES gradient for ADHD diagnoses and prescriptions was most pronounced in urban children 0 to 13 years of age. Otherwise, all main effects tested (sex, age, socioeconomic status, geographical region, and comorbid BD and LD) were significant in both the diagnosis and prescription models for ADHD. Policy considerations that arise out of this study include more stringent diagnostic and prescription treatment practices, additional support resources for children who are most at risk of having ADHD, and increased information about alternate treatment implementation for ADHD.

Studies have shown that including perennial forages in cropping rotations can increase soil carbon (C) and lower nitrous oxide (N2O) emissions when compared to continuous annual cropping. Research is needed to evaluate the inclusion of a perennial forage in an annual crop rotation on net carbon dioxide (CO2) and N2O fluxes, natural and agronomic drivers of seasonal greenhouse gases (GHGs), and the possibility of using forages as a C sequestration-CO2 mitigation tool. A long-term field experiment site to determine GHG budgets for Red River Valley cropping systems in Manitoba, Canada was used. The site consisted of four plots with the same annual rotation management history. A perennial legume, alfalfa, was grown in 2008 and 2009 on two plots and spring wheat and industrial oilseed-rapeseed grown on the other two plots in 2008 and 2009, respectively. Nitrous oxide and CO2 fluxes were measured continuously using the flux gradient micrometeorological method. For the net study period, the perennial phase sequestered twice the atmospheric CO2 (2070 kg C ha-1) compared to the annual crops. The annual rotation emitted 3.5 times more N2O than the perennial legume phase. When accounting for harvest C removals and considering GHGs in CO2-equivalent (eq.), the perennial legume phase was a net sink of 5440 kg CO2-eq. ha-1 and the annual rotation was a net source of 4500 kg CO2-eq. ha-1 for the two year study period. Information gathered will help bridge missing data gaps in national emission trends and enhance development of Canadian GHG mitigation models.

<p>Many cells are remarkably proficient at tracking even shallow chemical gradients, despite tiny differences in receptor occupancy across the cell. Stochastic receptor-ligand interactions introduce considerable noise in instantaneous receptor occupancy, so it is thought that spatial information must be integrated over time to allow noise filtering. The mechanism of temporal integration is unknown. We used the mating response of the budding yeast, <italic>Saccharomyces cerevisiae</italic>, as a model to study eukaryotic gradient tracking. </p><p>During mating, yeast cells polarize and grow up a gradient of pheromone to find and fuse with opposite-sex partners. Exposure to pheromone causes polarity regulators to cluster into a tight "patch" at the cortex, directing growth toward that site. Timelapse microscopy of fluorescently-labeled polarity proteins revealed that the patch wandered around the cortex during gradient tracking. Mathematical modeling and genetic analysis suggested that fusion of vesicles near the polarization site could perturb the polarity patch and promote wandering. Wandering is decreased due to global effects from pheromone signaling as well as interactions between receptor-activated G&beta; and the exchange factor for the polarity regulator Cdc42. We found that artificially stabilizing patch wandering impaired accurate gradient tracking.</p><p>We suggest that ongoing polarized vesicle traffic causes patch wandering, which is locally reduced by pheromone-bound receptors. Thus, over time, spatial information from the pheromone gradient biases the random wandering of the polarity patch so that growth occurs predominantly up-gradient. Such temporal integration may enable sorting the low signal from stochastic noise when tracking shallow gradients.</p> / Dissertation

No description available.

Chronic disease is a major health burden in the United States, affecting about half of adults, and leading to poor health, disability, and death. However, the burden of chronic disease is not shared equally among Americans, with some groups (created by determinants such as race/ethnicity and socioeconomic resources) experiencing higher rates of morbidity and mortality. When measures of health and socioeconomic resources are examined together, a stepwise gradient pattern emerges. This social gradient has been established for individual measures, such as household income and social class, and several measures of morbidity and mortality. However, nationally, little research has been conducted using area-level measures, such as county economics, to examine its relationship with chronic disease. Three studies were completed using data from the Behavioral Risk Factor Surveillance System (BRFSS). County economic status was determined using unemployment, per capita market income, and poverty. The first study examined the relationship between county economic status and chronic disease and risk factors, both nationally and by metropolitan classification, using data from BRFSS 2013. Further, the social gradient was explored. The second study also used data from BRFSS 2013 to examine county economic status and prevalence of hypertension, arthritis, and poor health, after controlling for known risk factors. This study also examined results by US region. Finally, the third study assessed changes in disparities between persistently poor and persistently affluent counties for heart disease, hypertension, arthritis, and diabetes using data from BRFSS 2001-2010.

Internal instability of a widely graded cohesionless soil refers to a phenomenon in which its finer particles migrate within the void network of its coarser particles, as a result of seepage flow. Onset of internal instability of a soil is governed by a combination of geometric and hydromechanical constraints. Much concern exists for embankment dams and levees built using soils with a potential for internal instability. Migration of finer particles to a boundary where they can exit, by washing out, may cause erosion or piping failure and, occasionally, induce collapse of these soil structures. There is a need, in professional practice, to better understand the phenomenon and to develop improved methods to evaluate the susceptibility of a soil. A series of permeameter tests was performed on six widely-graded cohesionless materials. The objectives are to assess the geometric indices proposed for evaluation of susceptibility, and examine hydromechanical factors influence the onset of internal instability. A modified slurry mixing technique, with discrete deposition, was found satisfactory for reconstitution of the homogeneous saturated test specimens. The onset of internal instability was founded to be triggered by a combination of effective stress and hydraulic gradient. The finding yields a hydromechanical envelope, unique for a particular gradation shape, at which internal instability initiated. Three commonly used geometric criteria were comprehensively evaluated with reference to these experimental data and also a database compiled from the literature. The relative conservatism of each criterion was examined and a modified semi-empirical geometric rule then proposed based on the capillary tube model. A theoretical framework for plotting the hydromechanical envelope was established based on an extension of the α concept of Skempton and Brogan, and subsequently verified by test data. Finally, a novel unified approach was proposed to assess the onset of internal instability, based on combining geometric and hydromechanical indices of a soil.