Safety Recommendations — The engine that drives change

The National Transportation Safety Board (NTSB) considers the recommendations it makes to prevent accidents and improve the safety of the United States transportation system to be its most important product.In its 25-year history the NTSB has made almost 9,000 safety recommendations covering needed improvements in all the modes of transportation to more than 1,250 recipients. These recommendations are made to anyone the NTSB believes can make the change that is necessary to improve safety. Recommendations have been directed to federal, State and local government agencies, private transportation companies, labor unions, trade associations and others.Overall, more than 80 percent of the NTSB's safety recommendations have been accepted by the recipients and the changes called for have been implemented. This has had a very significant positive impact on the safety of the US transportation system. The NTSB is very proud of this record. The changes that have taken place as a result of the NTSB's recommendations have saved thousands of lives and prevented many accidents.How has the NTSB achieved such a good record? The basic foundation and most important reason for this achievement is the NTSB's independence. This independence lends the NTSB credibility. Recipients of the NTSB's recommendations are more willing to carefully and seriously consider taking the action recommended. The second essential reason for the NTSB's credibility is the highly competent, technical qualifications of its investigators and the thoroughness of its investigations and studies. The NTSB also is very careful and prudent in making its recommendations. Each proposed recommendation is carefully evaluated to make sure it is practical, feasible and capable of being implemented. The credibility of the NTSB has grown over the years, and along with that has come an increase in the acceptance rate of the recommendations.This paper will describe the NTSB's safety recommendation program, how it achieves improved safety, and its important elements, such as the Most Wanted Safety Recommendation Program and the Safety Recommendation Information System.     

Integrating quality and quantity of mutualistic service to contrast ant species protecting Ferocactus wislizeni

Generalized, facultative mutualisms are often characterized by great variation in the benefits provided by different partner species. This variation may be due to differences among species in the quality and quantity of their interactions, as well as their phenology. Many plant species produce extrafloral nectar, a carbohydrate-rich resource, to attract ant species that can act as "bodyguards" against a plant's natural enemies. Here, we explore differences in the quality and quantity of protective service that ants can provide a plant by contrasting the four most common ant visitors to Ferocactus wislizeni, an extrafloral nectary-bearing cactus in southern Arizona. The four species differ in abundance when tending plants, and in the frequency at which they visit plants. By adding surrogate herbivores (Manduca sexta caterpillars) to plants, we demonstrate that all four species recruit to and attack potential herbivores. However, their per capita effectiveness in deterring herbivores (measured as the inverse of the number of workers needed to remove half of the experimentally added caterpillars) differs. Using these among-species differences in quality (per capita effectiveness) and quantity (number of workers that visit a plant and frequency of visitation), we accurately predicted the variation in fruit production among plants with different histories of ant tending. We found that plant benefits (herbivore removal and maturation of buds and fruits) typically saturated at high levels of ant protection, although plants could be "well defended" via different combinations of interaction frequency, numbers of ant workers per interaction, and per capita effects. Our study documents variation among prospective mutualists, distinguishes the components of this variation, and integrates these components into a predictive measure of protection benefit to the plant. The method we used to average saturating benefits over time could prove useful for quantifying overall service in other mutualisms.     

Monitoring of iodinated X-ray contrast media in surface water

A monitoring programme was carried out in order to determine iodinated X-ray contrast media (ICM) in the River Danube and to investigate the raw water quality for drinking water production at Langenau waterworks. The study revealed that the maximum concentrations of ICM (over 500 ng l(-1) for diatrizoic acid and iopamidol) were found in 2h-composite samples taken from the downstream of the Ulm/Neu-Ulm metropolitan area. By means of a concentration profile over one month the highest ICM concentrations were observed on weekdays. The extended data evaluation with principal component analysis shows that the upstream and downstream samples had different pattern of variations in ICM concentration and also demonstrates a clear change in ICM composition by the discharge of municipal wastewater. In addition to load profiles of ICM, time-dependent plots of principal component 1 exhibited peaks, indicating a short-term discharge of ICM between the two sampling sites. In conclusion, a point source for ICM contamination between the sampling sites in Ulm upstream and Leipheim downstream seems to be the reasonable explanation for peak ICM concentrations. Due to the observed high variations of ICM concentrations in river, the evaluation of natural waters by means of a single analysis is not representative.     

Lattice-based methods for regression and density estimation on complicated multidimensional regions

Environmental and Ecological Statistics - This paper illustrates the use of diffusion kernels to estimate smooth density and regression functions defined on highly complex domains. We generalize...     

Modelling gas release event behaviour in hazardous waste tanks

Certain radioactive waste storage tanks at the United States Department of Energy Hanford facilities continuously generate gases as a result of radiolysis and chemical reactions. The congealed sludge in these tanks traps the gases beneath it and causes the level of the waste within the tanks to rise. The waste level continues to rise until the sludge loses its buoyancy and rolls over, changing places with fluid on top. During a rollover, the trapped gases are released, resulting in a sudden drop in the waste level. This is known as a gas release event (GRE). After a GRE, the waste re-congeals and gas again accumulates, leading to another GRE. We are interested in the time between consecutive GREs. Understanding the probabilistic behaviour of the time between consecutive GREs is important because the hydrogen and nitrous oxide gases released during a GRE are flammable and the ammonia that is released is a health risk. From a safety perspective, activity around such waste tanks should be halted when a GRE is imminent. With a credible probability model for the time between consecutive GREs, we can establish time windows in which waste tank research and maintenance activities can be safely performed. We discuss the application of non-linear time series models to this problem.     

Probability distributions and statistical inference for axial data

Observations on axes which lack information on the direction of propagation are referred to as axial data. Such data are often encountered in enviromental sciences, e.g. observations on propagations of cracks or on faults in mining walls. Even though such observations are recorded as angles, circular probability models are inappropriate for such data since the constraint that observations lie only in [0, π) needs to be enforced. Probability models for such axial data are argued here to have a general structure stemming from that of wrapping a circular distribution on a semi-circle. In particular, we consider the most popular circular model, the von Mises or circular normal distribution, and derive the corresponding axial normal distribution. Certain properties of this distribution are established. Maximum likelihood estimation of its parameters are shown to be surprisingly, in contrast to trigonometric moment estimation, numerically quite appealing. Finally we illustrate our results by several real life axial data sets. Received: September 2004/ Revised: December 2004     

A role forAmanita muscaria L. in the circulation of cadmium and vanadium in a non-polluted woodland

The sporophore of the fungusAmanita muscaria L. contains greatiy elevated levels of cadmium (29.9 g g^–1 dwt) and vanadium (344.9 g g^–1 dwt) in comparison with the soil in a birch woodland (total (HNO₃-extractabie Cd 0.4 g g^–1 dwt, V 11.7 g g^–1 dwt). The significance of this remarkable concentration of normally rare and dispersed elements in terms of their circulation in the woodland has been investigated. Both elements are released from sporophore tissue in a form which can be taken up by a test plant (lettuce), cultivated in the woodland soil amended with different quantities of sporophore tissue, Cadmium levels in all plant tissues were elevated in comparison to the non-amended controls; only root vanadium levels responded to the amendment of the soil. The results are discussed in terms of their significance for the natural cycling of both elements. It is calculated that an abundant population of sporophores could circulate 1.4% of the total cadmium and 0.65% of the total vanadium pool found in the litter layer and 0–5 cm soil horizon in the sampled woodland over a period of 14 days (mean life span of a sporophore).     

Impending Recovery of Kirtland's Warbler: Case Study in the Effectiveness of the Endangered Species Act

Dendroica kirtlandii ). This particular recovery program actually began before passage of the federal ESA, when biologists alerted the Michigan Department of Natural Resources of the perilously low population of this bird, which only breeds under jack pine (Pinus banksiana) trees in Michigan. By the time an ESA Recovery Team was formed for this bird in 1975 (the first such team created under the ESA), a legacy of consensus and interagency cooperation was well established. This has led to successful efforts at habitat management and control of its nest parasite, the brown-headed cowbird (Molothrus ater). While the Kirtland's warbler is not yet recovered, its population is near an all-time high, and its recovery is possible within the next decade. When (and if) this happens, it will be clearly attributable to this successful model of federalism for natural resources management.