Understanding the Behavior of a Pile Foundation in Unsaturated Soils Subjected to Lateral Loading

The purpose of this research was to further understand the behavior of pile foundations in unsaturated soils subjected to lateral loading. Recent case histories show the importance of incorporating unsaturated soil mechanics in geotechnical engineering practice for the design and construction of resilient and cost effective systems. Unsaturated soils are a three phase material- solid, liquid and gas, resulting in three interfaces. Among the three interfaces the liquid-gas interface, also known as the contractile skin, plays a critical role in the mechanical and flow behaviors of unsaturated soil. The effects of the contractile skin are measured in terms of matric suction. Though unsaturated soil mechanics can be beneficial in engineering design, the concern of practitioners is the selection of the appropriate value of matric suction for the site based on rainfall and infiltration data. In addition to studying the behavior of pile foundations in unsaturated soils a method is proposed for characterizing an unsaturated soil profile for a site based on reliability concepts using a sample shallow foundation design. The research is divided into two types of lateral loading on piles in unsaturated soils: static cyclic loading and dynamic earthquake loading. A typical long and slender bridge pile in unsaturated soils is studied using geotechnical centrifuge modeling and finite element modeling. The development of a centrifuge model and test procedure for studying unsaturated soil-pile coupling behavior is developed. The soil container on the centrifuge is divided into three regions to allow for a cost effective way to collect a lot of data on a destructive model. The first region tests the dynamic response of a bridge pile with a representative superstructure at the top subjected to a given base motion, the second region tests the behavior of bridge pile subjected to slow cyclic loading, and the third region records the free field dynamic response for the applied motion at the base of the model. The steady state infiltration method was performed to create uniform degree of saturation profile while the centrifuge is spinning. Tests were conducted at two different degrees of saturation. Also, a dry test and a fully saturated test were also conducted for the purpose of comparing with the unsaturated responses. Data was collected on these four centrifuge tests for the three regions. Comparisons of responses are made between one dry sample and two different unsaturated soil profile samples. Overall the centrifuge tests provided useful data and the lessons learned from the test procedure will be applied to future physical models. The dynamic behavior of a bridge pile in unsaturated soil is simulated using an improved simplified finite element model, which incorporates the Rayleigh damping model into the formulation. In the modeling, the stress-strain behavior of the soil is modeled using an elastoplastic constitutive model for unsaturated soil based on a bounding surface concept. The pile is modeled by Timoshenko beam elements using a linear elastic model. The response of the pile and the soil is investigated at three initial degrees of saturation. The results show that the coupled soil-pile interaction is not largely affected by the range of initial degrees of saturation in this study. Since there is still a significant amount of work to create deterministic equations, p-y curves, and numerical models for laterally loaded piles in unsaturated soils. The method proposed for characterizing an unsaturated soil profile for a site using reliability methods was tested with a shallow foundation. The method uses Monte Carlo simulation to determine the bearing capacity of a footing using a semi empirical equation. The matric suction term in the equation is solved for using data from the U.S. National Climatic Data Center and U.S. Geological Survey National Water Information System. The results show increases in bearing capacity using the new method with factors as large as 2.7 times the capacity compared to deterministic approaches using saturated soil parameters. The paper also discusses the effect of the depth factor on the new dominating cohesion term in the bearing capacity equation. The results show that an increase in footing size results in smaller factors of increase in bearing capacity as suction increases the value of the cohesion term

The TeleTAnDem intervention - Study protocol for a psychotherapeutic intervention for family caregivers of people with dementia

Soellner R, Reder M, Machmer A, Holle R, Wilz G. The TeleTAnDem intervention - Study protocol for a psychotherapeutic intervention for family caregivers of people with dementia. BMC Nursing. 2015;14(11): 11

Optometric Care of the Patient with Diabetes

The Canadian Association of Optometrists (CAO) is the national voice of optometry and is dedicated to collaboratively advancing the highest standard of primary eye care through the promotion of optimal vision and eye health, in partnership with all Canadians. Optometrists are the front line of eye health and vision care. They are experts in primary eye care and are well-positioned to help combat the vision related complications of diabetes. CAO assembled the Diabetes Guidelines Working Group to create national guidelines on the clinical management of diabetes mellitus in an effort to further educate Canadian optometrists and assist them in the management of this chronic disease. The Working Group consists of optometrists from private practice, research and academia, chosen on the basis of their expertise, experience and representation from across Canada

Sex-Related Effects of an Immune Challenge on Growth and Begging Behavior of Barn Swallow Nestlings

Parent-offspring conflicts lead the offspring to evolve reliable signals of individual quality, including parasite burden, which may allow parents to adaptively modulate investment in the progeny. Sex-related variation in offspring reproductive value, however, may entail differential investment in sons and daughters. Here, we experimentally manipulated offspring condition in the barn swallow (Hirundo rustica) by subjecting nestlings to an immune challenge (injection with bacterial lipopolysaccharide, LPS) that simulates a bacterial infection, and assessed the effects on growth, feather quality, expression of morphological (gape coloration) and behavioral (posture) begging displays involved in parent-offspring communication, as well as on food allocation by parents. Compared to sham-injected controls, LPS-treated chicks suffered a depression of body mass and a reduction of palate color saturation. In addition, LPS treatment resulted in lower feather quality, with an increase in the occurrence of fault bars on wing feathers. The color of beak flanges, feather growth and the intensity of postural begging were affected by LPS treatment only in females, suggesting that chicks of either sex are differently susceptible to the immune challenge. However, irrespective of the effects of LPS, parents equally allocated food among control and challenged offspring both under normal food provisioning and after a short period of food deprivation of the chicks. These results indicate that bacterial infection and the associated immune response entail different costs to offspring of either sex, but a decrease in nestling conditions does not affect parental care allocation, possibly because the barn swallow adopts a brood-survival strategy. Finally, we showed that physiological stress induced by pathogens impairs plumage quality, a previously neglected major negative impact of bacterial infection which could severely affect fitness, particularly among long-distance migratory birds

A Mechanistic Approach to Understanding Range Shifts in a Changing World: What Makes a Pioneer?

AbstractA species’ range can be thought of as a manifestation of the ecological niche in space. Within a niche, evolution has resulted in traits that maximize fitness. Across millennia, natural oscillations in temperature have caused shifts in the geographic location of appropriate habitat and with corresponding changes in species’ ranges. Contemporary climate change and human disturbance may lead to rapid range expansion or contractions with largely unknown consequences. Birds provide an excellent case study of this phenomenon with some taxa expanding range and others contracting even to the point of extinction. What leads some populations to expand while others contract? Are there physiological and behavioral attributes of “pioneers” at the forefront of a range shift/expansion?The concept of allostasis provides a framework with which to begin to evaluate when a species will be able to successfully expand into new habitat. This tool allows the integration of normal energetic demands (e.g. wear and tear of daily and seasonal routines) with novel challenges posed by unfamiliar and human altered environments. Allostasis is particularly attractive because it allows assessment of how individual phenotypes may respond differentially to changing environments. Here, we use allostasis to evaluate what characteristics of individuals and their environment permit successful range expansion. Understanding variation in the regulatory mechanisms that influence response to a novel environment will be fundamental for understanding the phenotypes of pioneers

Restatement of the definition of isosterism with respect to excited species

The current definitions of isosterism are incomplete if excited species are considered; here any reasonable definition must include the specification of the valence state too. Implications of this are discussed. A criterion for the selection of consistent valence state energies is developed