Seismic effects of elevating bridges with steel pedestals in the southeastern United States

Steel pedestals have been used in the southeastern parts of the United States to elevate highway bridges and decrease the likelihood of vehicle collisions with bridge decks. However, the seismic performance of bridges elevated with steel pedestals is still unknown. To investigate the effect of elevating bridges with steel pedestals, this paper uses the results of previously conducted experimental tests to model the hysteretic behavior of three types of steel pedestals in a detailed 3D finite element model of a representative bridge. One short pedestal (with a height of 500 mm) and two tall pedestals (with a height of 850 mm) are studied. The structural responses of the studied bridge with the addition of steel pedestals are compared to the structural responses of the same bridge before elevation, where elastomeric bearings support the deck. This study considers five different locations in the southeastern United States and for each of them selects 20 artificial ground motions at two hazard levels of 2% and 10% probability of exceedance in 50 years. The selected artificial ground motions are applied to the representative bridge model in four cases: one case with elastomeric bearings and three cases with three studied pedestals. Because of the large amount of resulting data, a statistical effects model is employed. The statistical effects model is a statistical tool that uses the statistics of the data to investigate the effect of each studied parameter such as bearing type, bridge location and hazard level on the structural responses. Results show that elevating bridges with the studied steel pedestals decreases longitudinal and transverse deck displacements, longitudinal shear and moment in columns, cap beam moment and pounding force. In the transverse direction, elevating the bridge leads to an increase in the abutment force. Also, results show that the studied tall steel pedestals are more effective than the studied short steel pedestal in decreasing longitudinal shear and moment in columns and decreasing transverse deck displacements while offering a height advantage. A study of the stability of the pedestals in this paper shows that the three types of studied pedestals may become unstable in earthquakes, thereby serving as a means to help determine where the installation of steel pedestals would not seem detrimental.     

Projects as the content and process of change: The case of the health and safety laboratory

The relationship between managing change, and managing projects and programmes has been a matter of recent debate. This paper will contribute to this debate by exploring two dimensions — projects as the content of change, and projects as the process of change. Projects form the process of change when the organisational changes are managed as a project, and projects form the content of change when the intent of the change process is a managing by projects form of organisation. This exploration will be conducted through a single rich case, using Pettigrew's well-established context, content, process model of organisational change. In presenting the case we will identify the paradox that the organisational change towards managing projects is not itself managed as a project, and we suggest that this paradox provides a good opportunity for stimulating novel lines of enquiry in research on project organising.     

Absence of fractionation of mercury isotopes during trophic transfer of methylmercury to freshwater fish in captivity

We performed two controlled experiments to determine the amount of mass-dependent and mass-independent fractionation (MDF and MIF) of methylmercury (MeHg) during trophic transfer into fish. In experiment 1, juvenile yellow perch (Perca flavescens) were raised in captivity on commercial food pellets and then their diet was either maintained on unamended food pellets (0.1 μg/g MeHg) or was switched to food pellets with 1.0 μg/g or 4.0 μg/g of added MeHg, for a period of 2 months. The difference in δ(202)Hg (MDF) and Δ(199)Hg (MIF) between fish tissues and food pellets with added MeHg was within the analytical uncertainty (δ(202)Hg, 0.07 ‰; Δ(199)Hg, 0.06 ‰), indicating no isotope fractionation. In experiment 2, lake trout (Salvelinus namaycush) were raised in captivity on food pellets and then shifted to a diet of bloater (Coregonus hoyi) for 6 months. The δ(202)Hg and Δ(199)Hg of the lake trout equaled the isotopic composition of the bloater after 6 months, reflecting reequilibration of the Hg isotopic composition of the fish to new food sources and a lack of isotope fractionation during trophic transfer. We suggest that the stable Hg isotope ratios in fish can be used to trace environmental sources of Hg in aquatic ecosystems.     

High resolution SE-fMRI in humans at 3 and 7 T using a motor task

Object The sensitivity of spin echo (SE) experiments to blood oxygenation level dependent (BOLD) contrast was explored in a study of the same six subjects carried out at 3 and 7 T. Materials and methods Multi-slice, single shot, spin echo, echo planar images with a voxel size of 1 × 1 × 3 mm³ were acquired at three different echo times, during execution of a simple motor task. Results Significant activation was observed at all echo times at both field strengths. Analysis of the fractional signal change as a function of echo time indicated that the change in relaxation rate, ΔR ₂, at 7 T was −0.51 ± 0.14 s ⁻¹, which was 1.3 times larger than the value found at 3 T. Measurements of the percentage signal change on activation and temporal signal to noise ratio showed that there was an increase in the BOLD contrast to noise ratio (CNR) at 7 versus 3 T by a factor of 1.9. There was no overlap of areas of significant activation in the SE data acquired at either field strength with the site of large veins. Conclusion SE-BOLD CNR in motor cortex was found to increase significantly at 7 T compared with 3 T.     

Current Work on Furnaces and Data Analysis to Improve the Uniformity and Noise Levels for Metal Fixed Points

Ongoing work to improve the uniformity of vertically mounted furnaces, manufactured by Carbolite (e.g., Type TZF12/75—three-zone furnace capable of 1200 °C, with 75 mm inner bore) along the axis and across the working tube and/or equalizing block is reported. This involves adjusting the size of the end zones, the position of the control thermometers, and the use of cascade-control methods. Means regularly used at NPL to reduce electrical noise in some commercially available ac furnaces through a reduction in the voltage used to “fire” the heaters, and better use of thyristor controllers (by extending their cycle time) are described. The need to shield the controllers from local magnetic fields is described. With these measures, the electrical noise from ac furnaces can approach that of dc furnaces, without the large cost of a dc power supply. The application of new data analysis techniques (Allan deviation) will be shown to improve the representation of uninterrupted fixed-point traces (as used in ingot verification rather than PRT calibration). Reduction of statistical noise on the temperature measurements has been achieved for data on the freezing plateau by determining the statistically optimum averaging time. This shows that the statistical uncertainty in the determination of the temperature of a particular freezing plateau is less than 25 μK and that noise (drift) from other sources, possibly due to variations in room temperature, starts to become appreciable over periods longer than a few tens of minutes. The measurement of freezing and melting plateaux at this level is aided by the introduction of new ASL-F900 bridge(s), and quieter/larger standard resistor baths.     

Using the elaboration likelihood model to examine online persuasion through website design

To investigate the dynamics of online persuasion, this research uses the Elaboration Likelihood Model (ELM) to determine the effects of argument quality as a central route to influence attitude change versus design and social elements as peripheral routes to attitude change. Additional to this research is an examination of change in issue involvement as a mediator between central and peripheral routes leading to attitude change. Findings from a study involving 403 participants add to our understanding of ELM concerning the role of website design and how an individual’s level of issue involvement is a prerequisite to changing user attitudes.     

Designs as a searchable intellectual property right

This article reviews the nature and value of design protection, some current developments, how design protection relates to and complements other forms of intellectual property (IP), and how searches can be made.     

Obtaining DNA from a geographically dispersed cohort of current and former smokers: use of mail-based mouthwash collection and monetary incentives.

The feasibility of collecting DNA through the mail from a cohort of current and former smokers was assessed. Also examined was whether monetary incentives would increase response rates. A random sample of 300 subjects, stratified by 20 U.S. communities, was selected to participate. The sampling frame included the 6,726 people who were in both the Community Intervention Trial for Smoking Cessation (COMMIT) between 1988 and 1993 and the follow-up study in 2001, and who consented to being contacted again. Subjects were further randomized within communities to incentive arms of 10 US dollars, 2 US dollars, or 0 US dollars. A total of 110 usable samples were returned (37%), and the 10 US dollars incentive arm had the highest response (43%). Logistic regression revealed no significant predictors of sending a DNA sample, although in a larger study, similar-sized odds ratios would be statistically significant for subjects who received the 10 US dollars incentive and for those who were White, female, or college graduates or whose household incomes were more than 60,000 US dollars per year. The spectrophotometer-determined median DNA yield was 44.93 microg (range=4.00-425.86 microg). Assuming that 50 ng of DNA would be needed for polymerase chain reaction amplification to determine any given genotype, 80-8,517 runs would be attainable. Qualitative findings suggest several methodological improvements to boost response rates. Institutional review board requirements, which are standardized on the inpatient, clinical protocol model, stipulated that noninstitutionally based subjects needed a witness to initial and date every page as well as sign the consent form. This pilot study showed that this requirement could pose some challenges in population-based research.