Here we report on the oxygen isotope compositions of four proposed apatite reference materials (chlorapatite MGMH#133648 and fluorapatite specimens MGMH#128441A, MZ-TH, ES-MM). The samples were initially screened for 18O/16O homogeneity using secondary ion mass spectrometry (SIMS) followed by δ18O determinations in six gas source ratio laboratories (GS-IRMS) employing a variety analytical proto...

Union rent-seeking is considered a tax on f irm returns f rom investments in innovative activity. We examine this proposition by considering the responses o f f irms in a 1985 survey on R&D and product innovation. Consistent with our model, we f ind that innovative activity is significantly less important for union than for similar nonunion firms. We conclude that innovative activity may be an ...

Popularity of gamma-hydroxybutyric acid (GHB) is fairly stable among drug users, while the consumption of its chemical precursor, gamma-butyrolactone (GBL), is a growing phenomenon. Although conventional analytical methods allow to detect this substance in various matrices, linking a trace and a source is still a difficult challenge. However, as several synthesis pathways and chemical precursor...

Introduction Conclusions References

This paper compares the approach and resultant outcomes of item response models (IRMs) and classical test theory (CTT). First, it reviews basic ideas of CTT, and compares them to the ideas about using IRMs introduced in an earlier paper. It then applies a comparison scheme based on the AERA/APA/NCME 'Standards for Educational and Psychological Tests' to compare the two approaches under three ge...

In isotope ratio mass spectrometry (IRMS), any sample (S) measurement is performed as a relative-difference (δi) from a working-lab-reference (W), but the result is evaluated relative to a recommended-standard (D): δi. It is thus assumed that different source specific results (δi, δi ...) would represent their sources (S1, S2 ...), and be accurately intercomparable. However, the assumption has ...

Because GHB (gamma-hydroxybutyrate) is present in both blood and urine of the general population, toxicologists must be able to discriminate between endogenous levels and a concentration resulting from exposure. In this paper, we propose a procedure for the detection of exogenous GHB in blood by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). Following liquid-liquid a...

Abstract Indigenous Research Methodologies (IRMs) for considering cultural values of water are a missing component and wetlands management in Australia. On this dry, flat ancient continent Traditional Knowledge has been passed on from generation to millennia. The profound knowledge surface groundwater critical ensuring the survival peoples driest inhabited continent, through finding, re-finding...