Influence of Input Motion and Site Property Variabilities on Seismic Site Response Analysis

Seismic site response analysis evaluates the influence of local soil conditions on earthquake ground shaking. There are multiple sources of potential uncertainty in this analysis; the most significant pertaining to the specification of the input motions and to the characterization of the soil properties. The influence of the selection of input ground motions on equivalent-linear site response analysis is evaluated through analyses performed with multiple suites of input motions selected to fit the same target acceleration response spectrum. The results indicate that a stable median surface response spectrum (i.e., within ±20% of any other suite) can be obtained with as few as five motions, if the motions fit the input target spectrum well. The stability of the median is improved to ±5 to 10% when 10 or 20 input motions are used. If the standard deviation of the surface response spectra is required, at least 10 motions (and preferably 20) are required to adequately model the standard deviation. The influence of soil characterization uncertainty is assessed through Monte Carlo simulations, where variations in the shear-wave velocity profile and nonlinear soil properties are considered. Modeling shear-wave velocity variability generally reduces the predicted median surface motions and amplification factors, most significantly at periods less than the site period. Modeling the variability in nonlinear properties has a similar, although slightly smaller, effect. Finally, including the variability in soil properties significantly increases the standard deviation of the amplification factors but has a lesser effect on the standard deviation of the surface motions.     

Reliability of networks of three-state devices

A three-state device is a device that can exhibit two different types of failure mode, an “open” failure and a “shorted” failure. This paper treats networks whose arcs may experience these two failure modes in addition to the normal “success” state. The network is undirected and has two designated nodes as source and sink. Such a network is itself subject to each of the two failure modes, and the reliability problem considered is computation of the probability of each of the three states of the network. Our observation is that such problems are easily reduced to the usual two-state network reliability problem for which common techniques such as the factoring theorem are readily applicable.     

Social support and the well-being of persons with spinal cord injury living in the community.

100 men and 40 women (all aged 19–77 yrs) with spinal cord injury completed a social support questionnaire, the Center for Epidemiologic Studies Depression Scale, the Life Satisfaction Index Form A, and a single-item self-assessment of health status. A physician assessed the presence or absence of urinary tract infection from laboratory findings and determined the absence, presence, and severity of pressure ulcers from physical examination. Amount of social support was positively related to life satisfaction and physical well-being. Satisfaction with one's support network was associated negatively with depressive symptomatology and positively with life satisfaction. There were significant differences in the correlations between life satisfaction and total social support for men and women. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evidence for Phytodegradation of MTBE from Coupled Bench-Scale and Intermediate-Scale Tests

This paper presents methodologies and demonstrates the need to couple bench-scale and intermediate tree-scale experiments, to fully understand the transport and fate of organic contaminants, specifically methyl tert butyl ether (MTBE), in mature trees. Bench-scale experiments showed MTBE to be optimally taken up by small poplar saplings with a transpiration stream concentration factor of approximately 1, little or no degradation in soils and, nearly 100±20% recovery in the coupled water-plant-air system, indicating no measurable phytodegradation at the bench-scale. A large 14?ft tree chamber was designed to evaluate MTBE transport and fate through intermediate-scale (12?ft tall) poplar trees. Abiotic MTBE volatilization tests conducted in the tree chamber showed 100±20% MTBE mass recovery, thereby demonstrating the integrity of the large chamber and its air monitoring technique. In contrast, replicate intermediate-scale experiments conducted with large (12?ft) trees irrigated with a known mass of MTBE showed a deficit of MTBE mass recovery (65±20%) in replicate soil-tree-air systems monitored over a 2-week period. More significantly, tert butyl alcohol (TBA), a degradation product of MTBE, was detected in increasing concentrations in leaf biomass while MTBE concentrations in leaf biomass decreased as the experiment progressed. The MTBE mass recovery deficit, coupled with the detection of increasing TBA in leaf biomass, provides preliminary evidence of MTBE degradation in mature trees.     

Intellectual Differences Between Suburban Preschizophrenic Children and Their Siblings.

The intelligence test scores of 56 suburban school children who later became schizophrenic adults were found to be significantly lower than the intelligence test scores of their siblings on tests taken at the same ages. Early intellectual deficit of future schizophrenics which is not easily discernible in suburban children, whose intelligence test scores often are above average but near the average of their own schools, shows up in comparisons with the performance of their own siblings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Behavior of electrically small depletion mode MOSFETs at low temperature

Impurity freezeout has a substantial effect on the threshold and subthreshold characteristics of large depletion mode devices. Recent experiments on short and narrow channel depletion mode devices demonstrate that geometry effects are independent of temperature and comparable to those of enhancement mode devices. Reduction of the electrical device size does not alter the degree of impurity freezeout. To predict the behavior of small channel enhancement and depletion mode devices, freezeout effects and geometry effects can be directly superimposed. A simple qualitative model is used to describe the conditions under which the superposition is valid.     

A method differentiating between bacterial adhesiveness and invasiveness in cell culture monolayer

In order to differentiate between bacterial adhesiveness and invasiveness in cell culture monolayers, a method is reported which enables the same specimen to be examined by both scanning electron microscopy and Nomarski interference contrast microscopy. The source of error made by statistical variation when the two microscopical techniques are used individually is thus avoided.