MSCAGR (Soil Science) / Department of Soil Science / Soil resilience is the ability of a soil to recover its function or capacity after applied stress such as crusting. Some soils have high potential for recovery while others have poor resilience. Soils with poor resilience are much more vulnerable to degradation. Many soils in South Africa are susceptible to crust formation, which affects many soil surface properties and processes and hence productivity. The objectives of this study were to demonstrate how soil resilience to crust formation is affected by conventional tillage and conservation agriculture in selected soils in South Africa. Soil samples were collected from four different soils (Hutton, Shortland, Glenrosa and Dundee) using PVC pipes with the length of 20 cm and diameter of 5cm and scanned using micro xray computed tomography for total pores. Total porosity from Luvisols, Ferrosols, Leptsols and Fluvisols under both conventional tillage and conservation agriculture was used to find soil resilience index. Soil crusting was influenced by both soil texture and clay mineralogy. The dominance of kaolinitic mineral caused the soil to be more stable as compared to soil dominated by quartz. Luvisols, Ferrosols and Leptsols were more stable and had aggregate stability of 57%, 69,5% and 32,7%, respectively. On the other hand, Fluvisols had poor aggregate stability with the value of 14,2%. Total porosity was in the order of 34,3%>32,2%>23,5%>16,3% for Ferrosols, Luvisols, Leptsols and Fluvisols, respectively. Soil crusting influenced the total porosity. Tillage practices had influence on soil crust formation hence, total porosity of the soils. Total porosity was higher under conservation agriculture as compare to conventional tillage. Resilience total porosity was in the order of 37,5> 23,9> 4,1> -30,1 on Luvisols, Ferrosols, Leptsols and Fluvisols, respectively. Soil resilience to crust formation was influenced by tillage practices. Soil resilience of Luvisols, Ferrosols and Leptsols can be achieved through conservation agriculture however, soil resilience of Fluvisols can be achieved through conventional tillage. / NRF

MSCAGR (Soil Science) / Department of Soil Science / Accelerated soil erosion is a serious agricultural problem in South Africa limiting soil productivity and little it’s known about its effect on soil quality. This study aimed to provide a less laborious, less time consuming and inexpensive protocol of estimating the effects of accelerated erosion on the soil quality. An assessment was undertaken in sites showing threat of accelerated erosion using various direct physical soil quality indicators. Four sites with different soil types were identified at initial survey. In each of the sites, two areas were selected. These areas were then classified as Not Visibly Eroded (NVE) and Visibly Eroded (VE). Each measurement in all site was done in those area classified respectively. The most stable structure and consistency were observed in NVE areas. Medium and large stones were observed in VE areas in all soil types studied. The VE soils were lighter in colour compared to soil colour in NVE. Aggregate stability and moisture content were significantly higher for the NVE and VE areas. Difference in values of water stable aggregates between NVE and VE was clear which showed that stability of aggregates is important in determining soil susceptible to erosion. Bulk density values were slightly different for the two areas. However, there was no significant difference between the bulk density of NVE and VE. Differences between soil texture for NVE and VE areas are only apparent for the sand, clay and silt particles with no changes in textural class. For all soil types investigated, silt was vulnerable to accelerated erosion with respect to soil texture. The research has provided baseline protocol for using physical soil quality indicators to find out effects of accelerated erosion. Soil functionality is critical in the restoration process of soil quality, and the methods used here could be effectively applied in a broad range assessment of erosion impact. / NRF

Alkali-Aggregate Reaction (AAR) is one of the most harmful distress mechanisms affecting the serviceability and durability of concrete critical infrastructure worldwide. Over the past decades, several approaches and recommendations have been developed to assess the potential reactivity of aggregates in the laboratory and the efficiency of preventive measures (e.g., supplementary cementing materials – SCMs) to mitigate ASR in the field. Yet, recent findings suggest that the appropriate use of SCMs “only” delayed and does not entirely prevent ASR occurrence. Moreover, once ASR starts in the field, there is no “universal” solution that should be applied in various cases, and each situation should be evaluated as “unique”. Nevertheless, artificially triggering healing agents have been studied in the late years, thus presenting an interesting “physical” solution to reduce the ingress of water and recover damaged concrete elements, which could present an interesting solution for durability-related distress due to ASR. This Ph.D. project focuses on detailed laboratory investigations aiming first to understand the self-healing process of concrete (i.e., by the natural or engineered process). Then, its further influence on ASR-induced expansion and deterioration, either applied internally or externally to the concrete. To achieve this goal, concrete mixtures presenting a wide range of binder compositions, using distinct types of chemical admixtures (e.g., crystalline self-healing), and incorporating five different types/nature of highly reactive aggregates (i.e., coarse and fine) were combined to manufactured concrete specimens in the laboratory. Otherwise, in aging specimens, concrete samples were designed only with GU-cement as the binder material but incorporated two different types/nature of highly reactive aggregates. Then, the samples were exposed to ASR-induced development until they reached pre-determined expansion levels, in which a wide range of sealers and coating materials were applied on the surface of the affected specimens. Mechanical (i.e., stiffness damage test, modulus of elasticity, micro indentation, shear and compressive strengths) and microscopic (damage rating index and scanning electron microscopy) tests were performed on samples at different ages (up to two years of accelerated ASR development). The results show that besides changing AAR-kinetics, the different binder compositions or the chemical admixtures could modify the distress mechanism due to AAR. The addition of crystalline healing agents or their combination with SCMs in concrete not only delayed the development of inner damage but significantly lowered the compressive strength loss at equivalent expansion amplitudes than control specimens. Moreover, the combination of different binder materials modified the chemical and mechanical properties of the ASR-gel, changing its swelling properties and the further damage development in concrete. On the other hand, the wide range of surface treatments used were not able to alter ASR distress mechanism; yet, they changed ASR-kinetics. Moreover, their effectiveness to slower the reaction shows to be significantly influenced by the damage degree to which the surface treatment is applied. Finally, a comprehensive framework enabling the optimized selection of raw materials to prevent or mitigate ASR development is proposed.

京都大学 / 0048 / 新制・論文博士 / 博士(医学) / 乙第12920号 / 論医博第2095号 / 新制||医||1010(附属図書館) / 32130 / (主査)教授 髙橋 良輔, 教授 松田 文彦, 教授 瀬原 淳子 / 学位規則第4条第2項該当 / Doctor of Medical Science / Kyoto University / DFAM

No description available.

No description available.

This thesis studied unpaved highway shoulders, and in particular shoulders of lower volume asphalt pavements being overlaid. The primary objective was to better understand how different shoulder aggregates perform on lower volume routes with asphalt surfaces and relatively narrow shoulders. A literature review and an evaluation of a full-scale test section containing five aggregate categories in nine test sections over a thirty-four-month period were the primary efforts performed to evaluate unpaved highway shoulders. The study concluded shoulder width measurements were not especially informative, and that California Bearing Ratio measurements were only modestly informative. Crushed concrete outperformed all other aggregates, though the remaining aggregate categories (gravel, limestone, steel slag, and reclaimed asphalt pavement) also had a reasonable case for being moved forward toward possible specification updates. The primary recommendation of this thesis is to use the data contained herein to further shoulder aggregate specifications for the Mississippi Department of Transportation.

Cardiovascular disease (CVD) is the leading cause of death in the United States, and hypertension has been recognized as a major contributor to its manifestation and progression. Vascular smooth muscle cells control the tone and elasticity of vessels and their dysfunction in hypertension contributes to arterial remodeling and subsequent end organ damage. Evidence has indicated that the Endoplasmic Reticulum (ER) Unfolded Protein Response (UPR) may be compromised in hypertension, while the contribution of protein aggregate formation (a main driver of UPR activation) is undefined. Glucose regulated protein-78 (GRP78), a residential ER chaperone, acts to aid in the proper folding of nascent peptides during translation, while also acting as the primary signal transducer for UPR. We hypothesize overexpression of GRP78 can protect against Angiotensin II induced protein aggregation in vascular smooth muscle cells (VSMCs) to reduce pathological ER UPR signaling and hypertensive vascular remodeling. To test this hypothesis, we investigated protein aggregate induction by Ang II stimulation as well as ER UPR activation, and if overexpression of the ER-resident chaperone glucose regulated protein 78 (GRP78) could protect against these as well as VSMC remodeling markers: hypertrophy, collagen production and inflammation. Utilizing pre-amyloid oligomer (PAO) immunofluorescence staining to identify Ang II induction of amyloid in VSMCs, we found amyloid accumulation was maximal at 48h post stimulation, which could be prevented with adenoviral overexpression of GRP78. Ang II significantly induced ER stress markers p-IRE1α, p-PERK and cleaved ATF6 in VSMCs. Overexpression of GRP78 was able to attenuate these ER stress responders. Interestingly, shotgun proteomic analysis of triton X-100 insoluble aggregate fractions revealed proteostasis machinery enriched in Ang II treated VSMC aggregates (HSP70, VCP, CryAB), which were attenuated with GR78 overexpression. To investigate pathological VSMC remodeling markers, we found that Ang II induced VSMC collagen production, immune cell adhesion, VCAM-1 expression, and hypertrophy (via protein synthesis) which was attenuated by GRP78 overexpression. Utilizing a VSMC-promoter derived GRP78 overexpression mouse model (GRP78TG SM22α Cre-/- or GRP78TG SM22α Cre+/-), we investigated the effect of ER stress inhibition on Ang II induced vascular remodeling. Importantly, hypertrophy and fibrosis in the aorta and the cardiac vasculature were assessed by Masson’s Trichrome and Sirius red staining and found to be increased in Cre-/- mice, while Cre+/- were significantly protected. These effects were accompanied with a significant reduction in Ang II-induced aortic amyloid burden (PAO) and ER UPR signaling. Blood pressure was monitored via tail cuff which revealed GRP78 Cre+/- mice were not protected against Ang II induced hypertension. Overall, these findings indicate that VSMC protein aggregation activates the ER stress response and contribute to hypertensive vascular remodeling. Furthermore, therapeutically targeting this mechanism via overexpression of GRP78 may elude new pharmacological interventions for arterial stiffness, while addressing fundamental questions about the mechanisms involved. / Biomedical Sciences

This thesis addresses a long-standing puzzle in empirical econometrics: Does the size distribution of income matter in the aggregate consumption function? Current opinion on whether distribution matters is divided. There is also a lack of consensus (among those who believe distribution effects exist) on the nature of such effects; that is, whether a decrease or an increase in income inequality is needed to stimulate aggregate demand. In this thesis, the previous or existing tests are challenged on the grounds that they do not properly take into account the causal link between the variability of the marginal, not the average, propensity to consume (with respect to the income level) and the existence of distribution effects. This particular link is taken care of, however, if one tests for the linearity (in income) of the micro relation underlying one's aggregate consumption function. The rejection of the linearity hypothesis will establish the existence of distribution effects. Ex post, if the nonlinear relation is such that the marginal propensity to consume declines with income, it also follows that an equalization in the income distribution produces greater aggregate consumption. The theoretical contribution of this thesis lies in the clarification of these issues. On the empirical side, this thesis cautions against the casual use of the term "distribution effects". In the current income-current expenditure framework of the Keynesians, it refers to "the effect of a redistribution of real disposable income" on aggregate real consumers' expenditure. In the Permanent Income Hypothesis framework, however, it could mean either "the effect of a redistribution of real disposable income" or "the effect of a redistribution of real permanent income" on aggregate real consumption. In this thesis, the distributions of real disposable income and real permanent income are alternatively assumed to follow the lognormal density, and two conclusions are empirically determined: I. The distribution of real disposable income matters in the current income-current expenditure framework---this result is statistically significant at a 10% level after the correction for serial correlation and simultaneity bias. In particular, the estimates indicate that the marginal propensity to consume declines with the level of real disposable income and, hence, a decrease in inequality would stimulate aggregate demand. II. The elasticity of consumption out of real permanent income is unity; therefore, the distribution of real permanent income does not matter in the Permanent Income Hypothesis framework---this result is statistically. significant at all conventional levels of significance both before and after the correction for serial correlation. Both findings are based on aggregative time-series data for Canada. The consumer unit in this thesis is an individual income-recipient, and the data period is 1947-1976. Maximum-likelihood procedures have been used in the estimation, with proper allowance for across-parameter constraints. In the event of correction for serial correlation, the autocorrelation coefficient is constrained to the open-interval (+1,-1). The results are also double-checked by examining many avenues that might affect the nature of the outcomes. Another contribution of this study is the compilation of data on the distribution of pre-tax personal income (in current dollars) in Canada under the lognormality hypothesis. The parameters of this distribution are determined using the minimum chi-square method. Estimates of the variance (of logarithms of income) parameter show a slight increase in income inequality over the period 1946 to 1976. The data on this parameter are used to approximate the variance of logarithms for the distribution of real disposable income (while establishing result I) and also the same for the distribution of real permanent income (while establishing the result II). / Thesis / Doctor of Philosophy (PhD)

No description available.