An interpretation of initial stress and strain methods,and numerical stability

This paper explores similarities and differences between initial stress and initial strain methods of analyses. The author takes the position that both methods, although perhaps conceptually different, are actually numerically the same. A simple approach for providing closed-form stability criteria for explicit and implicit time-marching procedures is described. For the case of associated, non-hardening viscoplasticity the approach provides criteria which are identical to those of Cormeau for explicit schemes. An implicit time-marching scheme which avoids the compliance matrix inversions at the constitutive level is also presented. Like many other implicit methods, this implicit time-marching scheme is unconditionally stable for θ≥½. The connection between initial strain plasticity and an explicit viscoplastic time-marching scheme is also addressed.     

THE IMPACT-FLOOD CONNECTION: DOES IT EXIST?*

In a recent article in Terra Nova, Kristan-Tollmann and Tollmann (1994) suggested that the Biblical Flood can be explained by seven fragments of a comet that impacted the ocean at seven locations on Earth at 03.00h (C.E.T.) on 23 September, 9545 yr BP. We demonstrate that all the ‘geological proofs’ that allegedly support their conclusions are not supported by the available data on impact cratering. Their hypothesis is based on insufficient and ambiguous data, selective citation, and incomplete comprehension of previous research.     

XENON,OSMIUM, AND LEAD FORMED IN O-SHELLS AND C-SHELLS OF MASSIVE STARS

In this paper we show that the explosive products from O-shells of massive stars which contain ¹²⁴Xe with large overproduction factors do not contain any of the naturally occurring isotopes of Os and Pb. We show further that the explosive products from C-shells (explosive carbon burning) do contain Os and Pb along with Xe which is strongly enriched in r-Xe of anomalous isotopic composition. The composition of Os in this matter is probably s-like rather than r-like. Pb in this matter is enriched in ²⁰⁸Pb. The results and arguments of this paper have implications for studies of isotopic compositions of Xe, Os, and Pb in residues of the Allende and other carbonaceous chondrites.     

用电子束CT作冠状动脉血管造影

本文介绍用电子束ＣＴ作冠状动脉可视化造影的方法,说明本项成就的特征和在应用这项技术的局限性,并指出这种技术在临床上,可能成为新无创伤性的诊断工具。     

Literal solution for Hill's lunar problem

A computer program for the manipulation of power series in several variables is used to find the first order solution to Hill's lunar problem. The ratiom of the mean motion of the Sun to that of the Moon is kept as a formal parameter. The series inm are known to converge very poorly. It is shown how efficient algorithms among them the Lie transformation allow us to compute the series inm as far as they are needed. When the series are evaluated at Brown's numerical value form the results achieve or exceed his accuracy.     

Exact Brans-Dicke-Bianchi types-II,VIII, and IX stiff matter solutions

Exact solutions of the Brans-Dicke field equations of Bianchi types-II, VIII, and IX are derived. The solutions represent locally rotationally symmetric universes with stiff matter content.     

Provenance of Palaeozoic sandstones from the Carnic Alps (Austria): petrographic and geochemical indicators

An integrated approach of petrographic analysis, whole rock geochemistry and microprobe analysis has been applied to obtain information on the geodynamic development and the provenance for Ordovician to Permian siliciclastic successions exposed within the Carnic Alps (Austria). Sandstone detrital mode and geochemical results refine previous geodynamic interpretations. Late Ordovician samples indicate a stable craton and recycled orogenic and, possible, extensional setting. The Early Carboniferous is interpreted to represent a compressional environment, followed by a Late Carboniferous molasse-type foreland basin, and a Permian extensional geodynamic setting. Contrasting geochemical patterns of post-Variscan and Permian sequences suggest a rift setting. Electron microprobe data of detrital white mica also indicate changes in the provenance. Compositional data reflect a shift from low- to medium-grade metamorphic (Ordovician) to high-grade metamorphic (Carboniferous) to low- to medium-grade metamorphic and plutonic source rocks (Permian). Additionally, our data show that various chemical discrimination diagrams do not include all possible ranges of sandstones, and that high contents of detrital mica and ultra-stable heavy minerals may cause misclassification. Consequently, we propose the use of multi-method approach for provenance studies, including the control of geochemical data by modal analysis and heavy mineral investigations.