The phase diagram and thermodynamic data for the In-Ga-Sb system are fit with a model for the LII-V liquid phases, in which the enthalpy and excess entropy of mixing are quartic functions of the atomic fraction and th...
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The phase diagram and thermodynamic data for the In-Ga-Sb system are fit with a model for the LII-V liquid phases, in which the enthalpy and excess entropy of mixing are quartic functions of the atomic fraction and the enthalpy of mixing is a quadratic function of temperature. The Gibbs energy, enthalpy, and entropy of formation of the LII-V compounds are obtained as functions of temperature from the heat capacities and the standard enthalpy and entropy of formation at 298 K. The fits are quantitatively satisfactory and better than any hitherto obtained, particularly for the m-V liquidus lines and the ternary liquid. The partial pressures of Sb, and Sb-4 are calculated along the three phase curves of In1.uGauSb(s), and relations given to obtain the relative chemical potentials of In and/or Ga are from these. The enthalpy of mixing of the m-v liquids is calculated for a few hundred degrees above the compound melting points, where presently there are no data. Characteristics of an improved model are postulated.
Recovery from transient processor failures can be achieved by using optimistic message logging and checkpointing. The faulty processors roll back, and some/all of the non-faulty processors also may have to roll back. ...
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Recovery from transient processor failures can be achieved by using optimistic message logging and checkpointing. The faulty processors roll back, and some/all of the non-faulty processors also may have to roll back. This paper formulates the rollback problem as a closure problem. A centralized closure algorithm is presented together with two efficient distributed implementations. Several related problems are also considered and distributed algorithms are presented for solving them.
An improved W-1.8-Re-1.8 gel generator based on Zr tungstate is described. The influence of synthesis parameters and pre-treatment conditions on Re-1.8 elution yields and the W-1.8 breakthrough was studied with 0.1.M ...
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An improved W-1.8-Re-1.8 gel generator based on Zr tungstate is described. The influence of synthesis parameters and pre-treatment conditions on Re-1.8 elution yields and the W-1.8 breakthrough was studied with 0.1.M aqueous solution of NaCl at pH 5.3 to 7.3 as well as with some organic solvents. An elution efficiency of 80% was achieved during 3 month of explotation with 0.1.M NaCl at pH = 6.3. The W-1.8 breakthrough was 1.(-4) to 1.(-3)%. The W-1.8 breakthrough may be decreased to 1.(-6)% when converted into tandem generator with an alumina column. However, Re-1.8 yields are reduced by 8-1.% with a tandem generator.
Robinson has proposed the bundle-based decomposition algorithm to solve a class of structured large-scale convex optimization problems. In this method, the original problem is transformed (by dualization) to an uncons...
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Robinson has proposed the bundle-based decomposition algorithm to solve a class of structured large-scale convex optimization problems. In this method, the original problem is transformed (by dualization) to an unconstrained nonsmooth concave optimization problem which is in turn solved by using a modified bundle method. In this paper, we give a posteriori error estimates on the approximate primal optimal solution and on the duality gap. We describe implementation and present computational experience with a special case of this class of problems, namely, block-angular linear programming problems. We observe that the method is efficient in obtaining the approximate optimal solution and compares favorably with MINOS and an advanced implementation of the Dantzig-Wolfe decomposition method.
In this paper, we extend the partial deduction framework of Lloyd and Shepherdson, so that unfolding of non-ground negative literals and loop checks can be carried out during partial deduction. We show that the unifie...
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In this paper, we extend the partial deduction framework of Lloyd and Shepherdson, so that unfolding of non-ground negative literals and loop checks can be carried out during partial deduction. We show that the unified framework is sound and complete wrt well-founded model semantics, when certain conditions are satisfied.
A-currents were studied in acutely dissociated chick autonomic neurons. Switching from salines containing 4 mM Mg2+ to salines containing 4 mM Ca2+ caused a large positive shift in the voltage dependence of steady-sta...
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A-currents were studied in acutely dissociated chick autonomic neurons. Switching from salines containing 4 mM Mg2+ to salines containing 4 mM Ca2+ caused a large positive shift in the voltage dependence of steady-state inactivation, but had no effect on the voltage dependence or kinetics of activation, deactivation, the rate at which channels became inactivated, or the rate at which channels recovered from inactivation. This effect saturated with increasing concentrations of Ca2+. Other group IIA divalent cations were less effective than Ca2+, in the order Ca2+ > Ba2+ > Mg2+ = Sr2+. Application of 4 nM Mg2+ partially antagonized the effects of 4 mM Ca2+. The results suggest that divalent cations selectively alter the voltage dependence of steady-state inactivation by acting at sites accessible from the outside of the cell.
The olfactory bulb of many elasmobranch fishes is morphologically subdivided into distinct units or sub-bulbs immediately adjacent to the olfactory epithelium. We investigated this morphological feature in two species...
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The olfactory bulb of many elasmobranch fishes is morphologically subdivided into distinct units or sub-bulbs immediately adjacent to the olfactory epithelium. We investigated this morphological feature in two species of shark and one species of ray in order to understand its impact on the arrangement of the primary olfactory projections onto the bulb. Using anterograde tracing methods in vitro (biocytin) as well as in fixed tissue (DiI), we observed a direct segregated projection of the olfactory afferents onto the bulb. Application of tracers to the lateral part of the olfactory epithelium resulted in staining restricted to the this region of the bulb, whereas the same tracers applied to the medial part of the epithelium resulted in staining of the medial olfactory bulb. The sub-bulbs appear to be individual anatomical units that each receive input from the olfactory lamellae. Nissl and myelin staining as well as the Golgi method show that the cytoarchitecture of the sub-bulbs is not substantially different from that of other anamniotes. However, we did note the existence of two types of mitral cell, based on the morphology of their dendritic arborization. Type L cells exhibit a loose dendritic arborization, whereas type T cells are characterized by a dense, bush-like dendritic arborization. Both types of mitral cells lack basal dendrites.
作者：
MARX, L1. Program in Science
Technology and Society Massachusetts Institute of Technology 02139 Cambridge Massachusetts USA
Recent anxieties about the deterioration of the global environment have had the effect of intensifying the ambiguity that surrounds the social roles of scientists and engineers. This has happened not merely, as sugges...
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Recent anxieties about the deterioration of the global environment have had the effect of intensifying the ambiguity that surrounds the social roles of scientists and engineers. This has happened not merely, as suggested at the outset, because the environmental crisis has made their roles more conspicuous. Nor is it merely because recent disasters have alerted us to new, or hitherto unrecognized, social consequences of using the latest science-based technologies. What also requires recognition is that ideas about the social role of modern science and engineering are embedded in, hence mediated by, larger views of the world. Within such American worldviews, moreover, the status of science and engineering is closely bound up with their perceived effect upon the environment. In the dominant culture, accordingly, the respect given to scientists and engineers is in large measure dependent on their ability to play the central role assigned to them in the historical narrative about progress. As the ostensible heroes of that popular story, they are expected to lead the way in realizing the promise of prosperity and general well-being. The environmental crisis surely has diminished the credibility of that story, thereby causing the social role of science and engineering to seem more dubious — more ambiguous. To be sure, the crisis also may have the effect, for very different reasons, of increasing the power and responsibility of organized science. But the late twentieth-century task of damage control cannot possibly elicit anything like the respect accorded to organized science by the earlier belief in progress. It also is important to recall, finally, that the narrative of progress itself has undergone a disillusioning transformation. The early Enlightenment version of the story depicted scientists and engineers working in the service of a social and political ideal that all people could share. But the later technocratic concept of progress, with its sterile instrumentalist
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