10,990 research outputs found

    Device spot-laps spheres to very close tolerances

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    Device laps precise amounts of metal from high spots on a spherical body to correct minute surface imperfections. The device generates the lapped surface with reference to an existing true surface on the spherical workpiece. Lapping is performed by applying a rotary and oscillatory motion to the workpiece while the lapping tool is held on the workpiece high spot

    C3H2 observations as a diagnostic probe for molecular clouds

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    Recently the three-membered ring molecule, cyclopropenylidene, C3H2, has been identified in the laboratory and detected in molecular clouds by Thaddeus, Vrtilek and Gottlieb (1985). This molecule is wide-spread throughout the Galaxy and has been detected in 25 separate sources including cold dust clouds, circumstellar envelopes, HII regions, and the spiral arms observed against the Cas supernova remnant. In order to evaluate the potential of C3H2 as a diagnostic probe for molecular clouds, and to attempt to identify the most useful transitions, statistical equilibrium calculations were carried out for the lowest 24 levels of the ortho species and the lowest 10 levels of the para species. Many of the sources observed by Matthews and Irvine (1985) show evidence of being optically thick in the 1(10)-1(01) line. Consequently, the effects of radiative trapping should be incorporated into the equilibrium calculations. This was done using the Large Velocity Gradient approximation for a spherical cloud of uniform density. Some results of the calculations for T(K)=10K are given. Figures are presented which show contours of the logarithm of the ratio of peak line brightness temperatures for ortho-para pairs of lines at similar frequencies. It appears that the widespread nature of C3H2, the relatively large strength of its spectral lines, and their sensitivity to density and molecular abundance combine to make this a useful molecule for probing physical conditions in molecular clouds. The 1(10)-1(01) and 2(20)-2(11) K-band lines may be especially useful in this regard because of the ease with which they are observed and their unusual density-dependent emission/absorption properties

    Variability of Millennial-Scale Trends in the Geomagnetic Axial Dipole

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    The historical trend in the axial dipole is sufficient to reverse the field in less than 2 kyr. Assessing the prospect of an imminent polarity reversal depends on the probability of sustaining the historical trend for long enough to produce a reversal. We use a stochastic model to predict the variability of trends for arbitrary time windows. Our predictions agree well with the trends computed from paleomagnetic models. Applying these predictions to the historical record shows that the current trend is likely due to natural variability. Furthermore, an extrapolation of the current trend for the next 1 to 2 kyr is highly unlikely. Instead, we compute the trend and time window needed to reverse the field with a specified probability. We find that the dipole could reverse in the next 20 kyr with a probability of 2%

    Hollow spherical rotors fabricated by electroplating

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    Equatorial bands are fabricated to provide a locating fit for the hemispheres of hollow spherical rotors which are then jointed by electroplating. Several nonmagnetic materials may be used to form the joint, such as aluminum, copper, iron, gold, plantinum, and zinc

    Soft Black Hole Absorption Rates as Conservation Laws

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    The absorption rate of low-energy, or soft, electromagnetic radiation by spherically symmetric black holes in arbitrary dimensions is shown to be fixed by conservation of energy and large gauge transformations. We interpret this result as the explicit realization of the Hawking-Perry-Strominger Ward identity for large gauge transformations in the background of a non-evaporating black hole. Along the way we rederive and extend previous analytic results regarding the absorption rate for the minimal scalar and the photon.Comment: 20 Pages, 1 figur

    In situ evidence for renitrification in the Arctic lower stratosphere during the polar aura validation experiment (PAVE)

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    In-situ measurements of nitric acid (HNO3), ozone (O3), and nitrous oxide (N2O) were made from the NASA DC-8 during the Polar Aura Validation Experiment in January/February 2005. In the lower stratosphere (9–12.5 km, potential temperature 300–350 K) characteristic compact relationships were observed between all three gases. The ratio HNO3/O3 averaged 3.5 (±0.7) ppt/ppb. Samples with enhanced HNO3/O3 (\u3e4.0) were most abundant under the edge of the Arctic Polar vortex in airmasses with enhanced mixing ratios of both gases (\u3e400 ppb O3 and \u3e2000 ppt HNO3) and reduced mixing ratios of N2O (\u3c305 ppb), indicating air from higher levels in the stratosphere. Relationships to N2O in the anomalous samples under the vortex edge indicate that increases in HNO3/O3 reflect renitrification at DC-8 flight levels, with no indication of significant O3 loss. Renitrified air was only observed at potential temperatures above 340 K, and was most abundant on the PAVE flights on 27 and 29 January

    Positivism and the Separation of Law and Economics

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    The modem field of law and economics – that is, the application of economic analysis to legal subjects other than trade and business regulation – is now over thirty years old, but it remains controversial in the legal academy and, to a lesser extent, in the profession at large. Since its beginnings in the early 1960s, the economic approach has provoked substantial opposition and antagonism. The sources of this resistance, however, are a matter of dispute. Many economists and economically influenced lawyers attribute it to more traditional lawyers\u27 reluctance to learn a new and unfamiliar set of concepts and techniques. Critics of the economic approach offer a variety of other explanations. Some are skeptical of the utility of abstract theoretical modeling in the social sciences, others object to economics\u27 central behavioral assumption of rational choice, still others criticize economics\u27 supposed libertarian politics and ideological allegiance to laissez-faire. The explanation that has attracted the most attention by far is economics\u27 commitment to the efficiency criterion: proponents of the economic approach tend to argue that more traditional lawyers have not paid enough attention to efficiency, and its detractors tend to argue that economics inappropriately focuses on efficiency to the exclusion of other normative considerations. All these explanations, however, are too narrow. As with any conflict between rival disciplines, the underlying division between law and economics is methodological and cultural. The two fields use different rhetorics, different styles of discourse, different epistemologies, and different literary forms in developing and articulating their respective accounts of the world. Resistance to interdisciplinary exchange between lawyers and economists comes partly from the fact that neither group wishes to give up its own culture in favor of the other\u27s.5 It also comes, however, from the two sides\u27 failure to understand each other\u27s cultural practices in full context
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