An Analytical Investigation of Prestressed Beam Bridge Performance Before and After Widening

As traffic and congestion increase, so does the likelihood of collisions. The solution to this problem is usually through a rehabilitation process with two primary options: (1) widening/expansion of existing roadway and bridges and (2) complete replacement (new construction) of roadway and bridges. The first option is the most feasible and cost-effective. While roadway widening/expansion pose minimal issues, the same cannot be said of bridge widening. An existing bridge presents a multitude of challenges during the planning and design phases, during construction, and throughout the structure\u27s service life. Special attention is required in both the design and detailing of the widening in order to minimize construction and maintenance problems. The primary objective of this dissertation is to present a better understanding of structural behavior and capacity by studying an existing widened structure: a bridge that has been in service for over 40 years (constructed in 1972 and widened in 2002). The load demand on this bridge has doubled over the years. Consequently, the widened structural system is composed of four-span continuous prestressed concrete bridge segments. To better understand the widened 2002 bridge used in this study, an initial comparative analysis was performed, comparing the original 1972 bridge and the 2002 widened bridge. This comparative analysis included a determination of bridge capacity, distribution factors, and load-rating factors using current American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) Specifications design codes. However, the original codes used for the two bridges should also be noted, as follows: (1) the AASHTO Load Factor Design (LFD) Code was used for the original bridge; and (2) a combination of the AASHTO LFD and AASHTO LRFD Specifications were used for the existing widened bridge. Linear three-dimensional finite element models were developed for both bridges to obtain the maximum moment and shear values with varying HL-93 load cases for these analyses. To develop models that describe the possible existing condition of the 2002 widened bridge, a nonlinear model of one of the critical members in the structure was developed by changing the most critical parameters. The critical parameters are categorized as material properties and prestress losses. Sensitivity studies were conducted using parametric models for simulations with moving loads for the different load cases using the HL-93 truck. The load-rating and reliability indexes were computed for all the cases under different loading conditions. The parameters that have the most influence on load rating and reliability are also presented in the analyses. The information generated from these analyses can be used for better–focused visual inspection and widened bridge load rating criteria, and can also be used for developing a long–term widening structural monitoring plan. Additionally, this study will be used as a benchmark for future studies, and to establish a procedure and methodology for future bridge widening projects

A short-term in situ CO2 enrichment experiment on Heron Island (GBR)

Ocean acidification poses multiple challenges for coral reefs on molecular to ecological scales, yet previous experimental studies of the impact of projected CO2 concentrations have mostly been done in aquarium systems with corals removed from their natural ecosystem and placed under artificial light and seawater conditions. The Coral–Proto Free Ocean Carbon Enrichment System (CP-FOCE) uses a network of sensors to monitor conditions within each flume and maintain experimental pH as an offset from environmental pH using feedback control on the injection of low pH seawater. Carbonate chemistry conditions maintained in the −0.06 and −0.22 pH offset treatments were significantly different than environmental conditions. The results from this short-term experiment suggest that the CP-FOCE is an important new experimental system to study in situ impacts of ocean acidification on coral reef ecosystems

Evaluation of the contribution of 16 European beef production systems to food security

peer-reviewedContext Livestock production, and more particularly ruminants, is criticized for its low conversion efficiency of natural resources into edible food. Objective The objectives of this paper are to propose an evaluation of the contribution to food security of different European cattle farms through three criteria: 1) food production assessed by the amount of human-edible protein (HEP) and energy (HEE) produced at farm level, 2) feed-food competition at the beef production scale estimated in terms of net human-edible protein and energy and in terms of land used, and 3) food affordability assessed by the production cost of meat, protein and energy. Methods The analysis is based on 16 representative beef production systems in France, Belgium, Ireland, Italy and Germany and covers cow-calf systems, finishing systems, dairy and mixed dairy- finishing systems, with or without cash crops. Results and conclusions The results show that, at the farm level, systems producing both beef and milk or cereals have higher HEP and HEE production per hectare (up to 370 kg of HEP and 60,000 106J.ha−1) than specialized beef systems (up to 50 kg of HEP and 1600 106J.ha−1) and have lower production costs (approximately €6 kg−1 of HEP in mixed beef system and €29 kg−1 of HEP in a specialized cow-calf-fattener system). Beef systems are almost all HEE net consumers. Results are more variable concerning net HEP efficiency. The cow-calf enterprises are mostly net producers of HEP but, in order to produce human edible meat, these systems need to be combined with finishing systems that are mostly net consumers of HEP. In most cases, cow-calf-finishing systems are net consumers of HEP (between 0.6 and 0.7) but grass-based systems using very little concentrates or systems using co-products not edible by humans are net HEP producers. The grass-based systems use more land area per kilogram of carcass but a major part of this area is non-tilled land, thus these systems are not in direct competition with human food production. The lowest meat production costs are the finishing systems producing the most live weight per livestock unit (LU) per year and dairy systems in lowland which share the costs between milk and meat. Significance Although most of HEE and HEP efficient farms typically have higher meat production costs, some grassland based systems stand out positively for all indicators. These results pave the way for improvements of the contribution of beef production systems to food security. Graphical abstract Net Human Edible Protein and Energy Efficiencies of meat production (M_HEP_eff and M_HEE_eff)

Price elasticity of demand for tobacco in ireland

This short study is an attempt to estimate the price elasticity of demand for tobacco in Ireland. Tobacco was chosen, partly because of its importance as a source of tax revenue, and partly because of certain simplifying factors in its demand structure. These latter are the lack of close substitutes, the absence of stocks held by consumers, and the fact that it is used by all classes in the community

Hispanic/Latinx and Spanish Language Concordance Among Palliative Care Clinicians and Patients in Hospital Settings in California.

Background: Members of racial or ethnic minority groups utilize palliative care (PC) services less than non-Hispanic White patients and multiple factors contribute to this disparity. The impact of racial, ethnic, and language (REL) concordance between patients and clinicians has been demonstrated in general medical populations, but not in PC populations. We characterized the racial and ethnic composition and languages spoken of California PC clinicians and patients to examine clinical impacts of REL concordance. Methods: Using Palliative Care Quality Network data, 15 inpatient teams were identified in California that had collected data on patient race/ethnicity and language. Patient and clinician data were analyzed using means and medians for continuous variables, and chi-squared tests to explore similarities and differences between clinician and patient data. Results: 51 clinicians from nine teams completed the survey. The largest non-White and non-English speaking groups among patients and clinicians identified as Hispanic/Latinx (31.5% of patients, 16.3% of clinicians) and as Spanish speakers (22.6% of patients, 7.5% of clinicians). There was a significantly higher proportion of Hispanic/Latinx patients compared to clinicians (p-value 0.01), with Southern California demonstrating the largest difference (30.4% of patients vs. 10.7 % of clinicians, p-value 0.01). Similar proportions of patients and clinicians reported Spanish fluency (22.6% vs 27.5%, p-value 0.31). Discussion: We found significant differences in the racial/ethnic distributions of Hispanic/Latinx patients and clinicians in California, prompting consideration of whether a lack of representation of Hispanic/Latinx clinicians relative to the patient population may contribute to lower palliative care utilization among Hispanic/Latinx patients