Statistical software for risk analysis at the Savannah River Site

This paper describes statistical software developed at the Savannah River Site (SRS) to analyze event time of occurrence data extracted from fault tree data banks and/or user defined input data files. Five different distributions can currently be fit to the empirical data: normal, lognormal, exponential, Weibull and loguniform. Two goodness of fit tests, the Kolmogorov-Smimov one-sample test and the Chi-squared test, are used to determine how well a particular distribution fits the observed data. In addition, a comparison across fitted distributions is done to determine the most likely distribution fitting the data. A number of graphics can be generated illustrating the important characteristics of the data and how well each theoretical distribution fits the data. The theoretical distribution which best fits the observed data, the expected occurrence rate, and the probability of occurrence are used in fault tree analyses. Results from the SRS developed software were compared with commercially developed and tested software, SAS

Adhesion of oral streptococci to enamel and dental materials : studies using a flow chamber and microcalorimetry

Dental plaque formation on human teeth is the crucial etiologic factor in the pathogenesis of oral diseases: caries, periodontal diseases, and peri-implantitis. Dental plaque has been defined as a diverse community of microorganisms found on teeth as a biofilm, embedded in an extracellular polymer matrix of bacterial origin and including host components. Bacterial colonization starts with the adhesion of early colonizers, called pioneer bacteria, to the salivary pellicle on teeth as well as on dental materials within minutes after tooth cleaning. The early colonizers, mostly streptococcoci, contribute to plaque development and ultimately to oral diseases. Investigations of dental plaque, including bacterial adhesion, employ various in vivo and in vitro models and use microscopic methods to assess surface phenomena. The complexity of the oral environment makes it difficult to generate an in vitro system including all relevant aspects. The studies presented (paper I-III) were aimed to adapt two in vitro models, a flow chamber system and a microcalorimetric technique, for investigating adhesion of oral streptococci to human enamel, glass and different dental materials. The dental materials used for the flow chamber experiments (paper I + II) were titanium (Rematitan®M), gold (Neocast 3), ceramic (Vita Omega 900), composite (Tetric Ceram), and four different all-ceramics. The early colonizing Streptococcus sanguinis, S. oralis, and the caries-inducing S. mutans, and S. sobrinus were used as the model organisms. The saliva-coated materials were incubated with the bacteria in the flow chamber during one hour. Number and vitality of adhering bacteria were determined microscopically after staining. The results suggested that variations in the number and vitality of the adherent oral streptococci depend on the surface characteristics of the substrata and the acquired salivary pellicle. It also depended on the bacterial species, as S. mutans and S. sobrinus adhered about 10 x less than S. sanguinis and S. oralis. Isothermal Microcalorimetry (paper III) indeed allowed evaluation of initial bacterial adhesion of S. sanguinis to glass. Maximum heat flow measurements during adhesion were about 10 fold lower than during bacterial growth. Experiments showed that increased surface areas, provided by increased amounts of glass beads, were associated with higher energy release. Heat flow was higher when cells were suspended in human saliva than in PBS. Based on these results both methods appear to be applicable to study bacterial adhesion to new dental restorative or implant materials. Advantages and disadvantages of the methods are discussed

Erythropoietin release from baboom renal allografts treated with subcellular kidney cell fractions

No Abstract

The mandibular anterior repositioning appliance (MARA) - a report of three cases

INTRODUCTION : The MARA (Mandibular Anterior Repositioning Appliance) is a fixed functional appliance used in the treatment of mandibular deficiencies. AIMS AND OBJECTIVES : To demonstrate the clinical capabilities, treatment effects and the expected duration of treatment when using the MARA, therefore creating awareness of the MARA as a treatment alternative to other functional appliances designed for correction of Class II malocclusions. METHODS : A retrospective study exploring the anteroposterior dimensional changes in the maxilla and mandible brought about by the MARA and the associated treatment time. The samples were the first three cases treated by a clinician inexperienced with the clinical application of the MARA and served as an ideal introduction to the treatment technique. RESULTS : In this study mandibular growth stimulation and temporomandibular joint remodeling may have been the main contributing factors in the resolution/improvement of the Class II malocclusions under treatment. CONCLUSION : The MARA is a useful non-compliance appliance that produces exceptional treatment results when applied in combination with full fixed appliances. The changes observed were predominantly of a skeletal nature in the anteroposterior dimension. Maxillary growth restriction may also have played a role in the correction of these treated Class II abnormalities.http://www.sada.co.zaam2020Orthodontic

Effective T-odd P-even hadronic interactions from quark models

Tests of time reversal symmetry at low and medium energies may be analyzed in the framework of effective hadronic interactions. Here, we consider the quark structure of hadrons to make a connection to the more fundamental degrees of freedom. It turns out that for P-even T-odd interactions hadronic matrix elements evaluated in terms of quark models give rise to factors of 2 to 5. Also, it is possible to relate the strength of the anomalous part of the effective rho-type T-odd P-even tensor coupling to quark structure effects.Comment: 6 pages, 1 figure, RevTe