Pennsylvanian ichthyoliths from the Shawnee Group of eastern Kansas

24 p., 9 fig., 2 pl.http://paleo.ku.edu/contributions.htm

Geologic applications of Late Pennsylvanian ichthyoliths form the midcontinent region.

Ichthyoliths (microscopic fish skeletal debris comprised mainly of teeth, dermal denticles and mucous membrane denticles) are abundant and diverse in a wide range of lithologies and often occur in horizons which are otherwise unfossiliferous. However, very few studies have dealt with Late Paleozoic ichthyoliths due to the problems in identifying them. Through the use of a coded system of identification, I have been able to overcome these taxonomic problems and utilize ichthyoliths. This study was conducted to assess the applicability of Late Pennsylvanian ichthyoliths in geology by comparing their geographic and stratigraphic distributions with those of the conodonts from the Shawnee and Lansing groups.Ichthyoliths from 16 localities extending from northern Oklahoma to Iowa were examined to determine their geographic and biostratigraphic distributions. Nearly 25,000 ichthyoliths comprising 156 different types were identified and used in the analyses. The results show that the distribution of ichthyoliths closely reflects that of conodonts in the Shawnee and Lansing groups. Different ichthyolith faunas were recovered from rock sequences of different ages, indicating a strong potential of ichthyoliths for biostratigraphic correlations. Initial studies to determine the reactions of ichthyoliths to thermal gradients show that they undergo not only color changes but structural alterations as well. Their thermal changes suggest an important use of ichthyoliths for hydrocarbon exploration. The results of this study indicate that Late Paleozoic ichthyoliths can provide useful information regarding biostratigraphy, geographic variation and geothermometry

Rank estimation of emission excitation matrixes using frequency analysis of eigenvectors

The number of components in mixtures of fluorophores Is determined by using a new method for matrix rank estimation of excitation-emission matrix (EEM) formated data. Mixture EEMs are decomposed into a set of basis vectors (eigenvectors) using eigenvector analysis. These vectors are then Fourier transformed and their frequency distributions are used as a means of differentiating between primary (spectral) eigenvectors and secondary (noise) eigenvectors. Primary eigenvectors are found to have Fourier spectra weighted toward the lower frequency coefficients, whereas Fourier spectra of secondary eigenvectors are found to be weighted toward the high frequency coefficients. An empirical algorithm for rank estimation based on the frequency distributions of eigenvectors is compared to traditional rank estimation methods. Finally, the method developed in this study is applied to 12 blind coded EEMs of mixtures of polynuclear aromatic hydrocarbons of known composition. © 1986, American Chemical Society. All rights reserved

Randomised double-blind placebo-controlled trial of SPf66 malaria vaccine in children in northwestern Thailand

Background. Previous efficacy trials of SPf66 malaria vaccine have produced conflicting results in different populations. We report a randomised double-blind trial of the SPf66 vaccine conducted in Karen children aged 2-15 living in a malarious region of northwestern Thailand. Recombinant hepatitis B vaccine was used as a comparator. Methods. The study had a power of 90% to detect an efficacy of 30%, defined as a reduction in the incidence of first cases of symptomatic falciparum malaria after three doses of vaccine. 1221 children received three immunisations and were eligible for the primary efficacy analysis. Intense active and passive case detection continued over 15 months of follow-up. Findings. The SPf66 vaccine was well tolerated, although 26 children had mild or moderately severe local or systemic allergic reactions, compared with none in the comparator group. The vaccine was immunogenic; after three doses, 73% of recipients had seroconverted. There were no deaths due to malaria during the study. During the 15-month period of evaluation there were 379 first cases of symptomatic falciparum malaria (195 in the SPf66 recipients, 184 in the comparator group); an SPf66 efficacy of -9% (95% CI -33 to 14, p = 0.41). No significant differences between the two study groups in parasite density or any other measure of malaria-related morbidity were detected. Interpretation. These findings are consistent with a recent study showing lack of efficacy of SPf66 among Gambian infants and differ from earlier positive reports from South America and evidence of borderline efficacy from Tanzania. We conclude that SPf66 does not protect against clinical falciparum malaria and that further efficacy trials are not warranted