1,902 research outputs found

    Early Archean tonalite gneiss in the upper peninsula of Michigan

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    Geochronological results on tonalite gneiss of northern Michigan that is 3.56 Ga or slightly older is presented. Tonalitic augen gneiss and structurally overlying biotite gneiss and schist are exposed in a dome near Watersmeet. They are part of an extensive gneiss terrane of southern Minnesota, Wisconsin and Michigan that includes rocks of early to late Archean ages and lies south of the Wawa volcanic subprovince. Two samples of the augen gneiss and one of the biotite gneiss show zircon grains of similar shape, zoning, color, and development of crystal faces. These zircons give Pb/U isotopic ratios that plot on a chord of 3,560 + or - 40 m.y. upper intersect and of 1,250 + or m.y. lower intersect. The 3,560 m.y. number is believed to be a minimum age because analysis of one of the least discordant zircon fractions by ion microprobe that gave a nearly concordant age of 3,650 m.y. The 1,250 m.y. lower intersect is without geological significance: it is interpreted to be a result of multiple lead loss at 2.7, 1.8, and 0.5 Ga by U/Pb in zircon. Archean rocks 10 to 25 km northwest of the Watersmeet dome give a 2.75 Ga age on zircons. Quartz monzonite here is dated at 2.65 Ga

    Fail-Safe vs. Safe-Fail Catastrophes

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    This paper is meant to serve two purposes. First, to extend the usefulness of catastrophe theory as a tool to aid our perception of a partially known world. This theory is a newly emerged branch of topology and, as such, begins to fill a large void in our arsenal of qualitative analytical tools. It is not appropriate for all important and interesting situations, particularly those requiring precise numerical results. But it is hoped that it can provide an important missing element for our environmental management tool kit. The second purpose is to report upon some deliberations precipitated by a recent paper of Beer and Casti (1975). We shall follow, to some degree, their development. We shall also borrow some of their examples and terminology in order to emphasize some fundamentally different strategies for managing unexpected events

    Studies of the use of high-temperature nuclear heat from an HTGR for hydrogen production

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    The results of a study which surveyed various methods of hydrogen production using nuclear and fossil energy are presented. A description of these methods is provided, and efficiencies are calculated for each case. The process designs of systems that utilize the heat from a general atomic high temperature gas cooled reactor with a steam methane reformer and feed the reformer with substitute natural gas manufactured from coal, using reforming temperatures, are presented. The capital costs for these systems and the resultant hydrogen production price for these cases are discussed along with a research and development program

    Grenville Foreland Deformation and Sedimentation in Southwest Ohio Indicated by Reprocessed Seismic Reflection Profiles near Middletown, Ohio, USA

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    The late Mesoproterozoic to early Neoproterozoic Middle Run Formation contains vital information about the crustal evolution of the North American Craton. Four reprocessed seismic reflection lines in the vicinity of the AK Steel facility in Middletown, Ohio, provide new insights into the structural and depositional setting of the Middle Run Formation in this region. A residual statics solution improved the resolution and coherency of reflections in these profiles that underlie the Cambrian Mount Simon Sandstone. Reprocessing revealed gently inclined, west-southwest-dipping reflectors and the occurrence of an angular unconformity between the Middle Run Formation and the overlying Paleozoic strata. The weak and discontinuous seismic reflection character of the Middle Run Formation in these seismic lines overlies a sequence of stronger parallel reflections that are like those observed on the eastward ODNR-1-88 seismic line located near core hole DGS 2627, the stratotype of the Middle Run Formation. This inferred thickness indicates that the basin in which the Middle Run Formation was deposited ranges from at least 670 to 1,128 m (2,200 to 3,700 ft) deep at the AK Steel area and dips gently west-southwest, which is in contrast with the moderate easterly dip observed on the ODNR-1-88 seismic line to the northeast. Correlation of these features across the 10 km (approximately 6 mi) cross-strike gap between the AK Steel lines and the ODNR-1-88 seismic line suggests the presence of a reverse fault with approximately 792 m (2,600 ft) of estimated vertical displacement. A regional cross section—including the WSU 1990 seismic line eastward of the ODNR-1-88 line—exhibits a faulted west-verging asymmetric syncline in near proximity to the Grenville Front. This cross section also shows that deformation of the Middle Run Formation and the underlying layered sequence exhibits a consistent tectonic style of reverse faulting and folding that developed in response to Grenville Front tectonism

    Martha Nussbaum and the rise of raunch culture: implications of the capabilities approach in the United States

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    This paper explores the effects of and also the limits to Martha C. Nussbaum's capabilities approach within the United States. Quite often in Nussbaum's work, her universal theory of justice is analyzed only within the context of developing nations, leaving readers to assume that persons living in the Third World are far more oppressed than those living in the West. By examining the capabilities approach, specifically the bodily integrity capability, within a Western context I aim to reveal (1) the corresponding inequalities existing in the U.S.; (2) which highlight Nussbaum's colonialist viewpoint; (3) in order to demonstrate that if issues of injustice are at the heart of Nussbaum's theory, creating hierarchies of oppression present a number of problematics when devising strategies to eradicate inequality

    Degradation Studies of Cyanex 301

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    International audienceDespite the numerous studies found in the literature on CYANEX® 301, very few explain its degradation in depth. To the best of our knowledge none has explained the inconsistency between the “common knowledge” of “CYANEX® 301 degrades into CYANEX® 272” (dithiophosphinic acid degrading into the corresponding phosphinic acid) and the 31P spectrum obtained by NMR of the degradation compound. The 31P {1H} NMR analysis of a solution of CYANEX® 301 in prolonged contact with nitric acid shows a very complex spectrum, with resonances about 20 ppm downfield from what could have been expected.The degradation product giving those multiple resonances in a pattern that could be interpreted as a triplet of triplet is actually a dimer, where two molecules of CYANEX® 301 are linked by a disulfide bridge, corresponding to the condensation of the SH groups. The explanation of the complexity of the spectrum comes from the comparison with the spectrum obtained for the degradation of a stereoisomerically-purified CYANEX® 301. This purification led to the removal of the [R;S] and [S;R] isomers from the initial mixture, and yielded a white crystalline solid proven to comprise exclusively [R;R] and [S;S] isomers by XRD analysis. It was determined that the carbon chirality induced an asymmetry of the phosphorus atoms upon condensation, leading to a wide combination of magnetically non-equivalent P-31 nuclei, which can also exhibit coupling through the S-S bond The complete explanation of the NMR spectra was established and corroborated by elemental analysi

    Optical properties and electronic structure of β′−NiAl

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    The optical constants and their temperature derivatives have been determined for β′−NiAl from absorption and thermoreflectance measurements in the energy range of 0.2-4.4 eV. The results are interpreted using the self-consistent energy bands of Moruzzi, Williams, and Gelatt. By comparing a calculated joint density of states with ε2, the imaginary part of the dielectric function, good overall agreement is found between theory and experiment. In contrast to earlier analyses, it is found that the 2.5-eV peak in ε2 is primarily due to direct interband transitions terminating near the Fermi surface. This new interpretation of the 2.5-eV feature is discussed in relation to previously reported concentration effects and the rigid-band model
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