Oxygen isotope studies on the origin of tektites

O^(18)/O^(16) ratios of thirteen tektites from Czechoslovakia, Libya, Texas, Indochina, Philippine Islands, Australia, Java, and Peru have been determined by the fluorine-extraction technique. All but one of these lie in relatively restricted range of O^(18)/O^(16) ratio, with δ = 9.6 to 10.4 per mil relative to the ocean-water standard. Tektites are therefore 0.5 to 1.5 per mil heavier than average granitic igneous rocks or about the same as average igneous quartz. The sample from Macusan, Peru (δ = 12.0), is anomalous and is probably not a true tektite. Six analyzed shales are isotopically heavier than tektites and show a much wider range in values (δ = 14.2, 14.8, 15.3, 15.5, 17.6, 18.2). Several detrital sedimentary rocks previously analyzed by Silverman and the present authors have δ values of 10.2 to 15.5; analyzed metasedimentary rocks have δ values of 12.1 to 15.7 per mil. Therefore, tektites are not sedimentary or metasedimentary material fused by lightning or by impact of an astronomical body with the earth. Chemically, tektites are unlike terrestrial igneous rocks, and their oxygen isotopic composition is unlike that of sedimentary or metasedimentary rocks. They therefore may be extraterrestrial objects

Correlations between O^(18)/O^(16) ratios and chemical compositions of tektites

The limits of oxygen isotope variation in tektites have been determined by analyzing 33 tektites that cover the widest possible spectrum of chemical compositions. δO^(18) values were obtained for 7 australites (8.9 to 11.0), 4 javaites (9.4 to 10.0), 3 indochinites (9.3 to 10.6), 5 philippinites (9.8 to 10.6), 8 moldavites (10.7 to 11.8), and 6 Ivory Coast tektites (13.0 to 13.6), as well as 2 samples of Darwin glass (14.4 to 14.9). Various tektite groupings based on chemical composition and geographic occurrence all show a systematic increase in O^(18) with decreasing SiO_2 content, similar to that previously found for the bediasites. These systematic correlations must arise either by (1) vapor fractionation of tektite material during impact melting or (2) mixing of a SiO_2-rich igneous component and a low-SiO_2 component formed at a much lower temperature; perhaps the mixing occurred during weathering at the earth's surface or during hydrothermal alteration of silicic igneous rocks either on the earth or the moon

The Emergence of Norms via Contextual Agreements in Open Societies

This paper explores the emergence of norms in agents' societies when agents play multiple -even incompatible- roles in their social contexts simultaneously, and have limited interaction ranges. Specifically, this article proposes two reinforcement learning methods for agents to compute agreements on strategies for using common resources to perform joint tasks. The computation of norms by considering agents' playing multiple roles in their social contexts has not been studied before. To make the problem even more realistic for open societies, we do not assume that agents share knowledge on their common resources. So, they have to compute semantic agreements towards performing their joint actions. %The paper reports on an empirical study of whether and how efficiently societies of agents converge to norms, exploring the proposed social learning processes w.r.t. different society sizes, and the ways agents are connected. The results reported are very encouraging, regarding the speed of the learning process as well as the convergence rate, even in quite complex settings

Joint Employment: The Unintended and Unpredictable Employment Relationship

The following is a transcript of a 2018 Federalist Society panel entitled Joint Employment: The Unintended and Unpredictable \u27Employment\u27 Relationship. The panel originally occurred on November 15, 2018, during the National Lawyers Convention in Washington, D.C. The panelists were: Richard Epstein, Laurence A. Tisch Professor of Law and Director, Classical Liberal Institute, New York University Law School; Richard F. Griffin, Jr., Of Counsel, Bredhoff & Kaiser, PLLC; and Hon. Philip A. Miscimarra, Partner, Morgan, Lewis & Bockius LLP. The moderator was the Honorable Timothy M. Tymkovich of the United States Court of Appeals for the Tenth Circuit

Using Factor Mixture Models to Evaluate the Type A/B Classification of Alcohol Use Disorders in a Heterogeneous Treatment Sample

BACKGROUND: The type A/B classification model for alcohol use disorders (AUDs) has received considerable empirical support. However, few studies examine the underlying latent structure of this subtyping model, which has been challenged as a dichotomization of a single drinking severity dimension. Type B, relative to type A, alcoholics represent those with early age of onset, greater familial risk, and worse outcomes from alcohol use. METHOD: We examined the latent structure of the type A/B model using categorical, dimensional, and factor mixture models in a mixed gender community treatment-seeking sample of adults with an AUD. RESULTS: Factor analytic models identified 2-factors (drinking severity/externalizing psychopathology and internalizing psychopathology) underlying the type A/B indicators. A factor mixture model with 2-dimensions and 3-classes emerged as the best overall fitting model. The classes reflected a type A class and two type B classes (B1 and B2) that differed on the respective level of drinking severity/externalizing pathology and internalizing pathology. Type B1 had a greater prevalence of women and more internalizing pathology and B2 had a greater prevalence of men and more drinking severity/externalizing pathology. The 2-factor, 3-class model also exhibited predictive validity by explaining significant variance in 12-month drinking and drug use outcomes. CONCLUSIONS: The model identified in the current study may provide a basis for examining different sources of heterogeneity in the course and outcome of AUDs

Diagnosis of high-temperature implosions using low- and high-opacity Krypton lines

High-temperature laser target implosions can be achieved by using relatively thin-shell targets, and they can be. diagnosed by doping the fuel with krypton and measuring K-shell and L-shell lines. Electron temperatures of up to 5 keV at modest compressed densities ({approximately}1-5g/cm{sup 3}) are predicted for such experiments, with ion temperatures peaking above 10 keV at the center. It is found that the profiles of low-opacity (optically thin) lines in the expected density range are dominated by the Doppler broadening and can provide a measurement of the ion temperature if spectrometers of spectral resolution {Delta}{lambda}/{lambda} {ge} 1000 are used. For high-opacity lines, obtained with a higher krypton fill pressure, the measurement of the escape factor can yield the {rho}R of the compressed fuel. At higher densities, Stark broadening of low-opacity lines becomes important and can provide a density measurement, whereas lines of higher opacity can be used to estimate the extent of mixing

Frictional sliding in layered rock: laboratory-scale experiments

The work is part of the rock mechanics effort for the Yucca Mountain Site Characterization Program. The laboratory-scale experiments are intended to provide high quality data on the mechanical behavior of jointed structures that can be used to validate complex numerical models for rock-mass behavior. Frictional sliding between simulated rock joints was studied using phase shifting moire interferometry. A model, constructed from stacks of machined and sandblasted granite plates, contained a central hole bore normal to the place so that frictional slip would be induced between the plates near the hole under compressive loading. Results show a clear evolution of slip with increasing load. Since the rock was not cycled through loading- unloading, the quantitative differences between the three data sets are probably due to a ``wearing-in`` effect. The highly variable spatial frequency of the data is probably due to the large grain size of the granite and the stochastic frictional processes. An unusual feature of the evolution of slip with increasing load is that as the load gets larger, some plates seem to return to a null position. Figs, 6 refs