472 research outputs found

    TAP reactor investigation of methane coupling over samarium oxide catalysts

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    The adsorption and reaction characteristics of a Ba/Sr/Sm2O3 catalyst for methane coupling has been investigated using the TAP (Temporal Analysis of Products) reactor system. Pulsed adsorption experiments using methane, oxygen and krypton at temperatures ranging from 17°C to 800°C show that the transient response of methane is similar to that of Kr and is either not adsorbed, or weakly adsorbed on the catalyst. By contrast, oxygen is strongly adsorbed at temperatures above 500°C which suggests incorporation into the lattice with possible formation of surface anions. Pump-probe experiments in which methane and oxygen are introduced over the catalyst were also performed to investigate the effect of lifetimes of suspected surface intermediates on the relative yields of ethane and ethene. It is shown that the relative yields of both species increase with increasing values of the pulse valve time delay between introduction of the oxygen and methane. An explanation of these results using current knowledge and reasonable speculation of the mechanism is provided

    ASMs and Operational Algorithmic Completeness of Lambda Calculus

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    We show that lambda calculus is a computation model which can step by step simulate any sequential deterministic algorithm for any computable function over integers or words or any datatype. More formally, given an algorithm above a family of computable functions (taken as primitive tools, i.e., kind of oracle functions for the algorithm), for every constant K big enough, each computation step of the algorithm can be simulated by exactly K successive reductions in a natural extension of lambda calculus with constants for functions in the above considered family. The proof is based on a fixed point technique in lambda calculus and on Gurevich sequential Thesis which allows to identify sequential deterministic algorithms with Abstract State Machines. This extends to algorithms for partial computable functions in such a way that finite computations ending with exceptions are associated to finite reductions leading to terms with a particular very simple feature.Comment: 37 page

    The ethical challenge of Touraine's 'living together'

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    In Can We Live Together? Alain Touraine combines a consummate analysis of crucial social tensions in contemporary societies with a strong normative appeal for a new emancipatory 'Subject' capable of overcoming the twin threats of atomisation or authoritarianism. He calls for a move from 'politics to ethics' and then from ethics back to politics to enable the new Subject to make a reality out of the goals of democracy and solidarity. However, he has little to say about the nature of such an ethics. This article argues that this lacuna could usefully be filled by adopting a form of radical humanism found in the work of Erich Fromm. It defies convention in the social sciences by operating from an explicit view of the 'is' and the 'ought' of common human nature, specifying reason, love and productive work as the qualities to be realised if we are to move closer to human solidarity. Although there remain significant philosophical and political differences between the two positions, particularly on the role to be played by 'the nation', their juxtaposition opens new lines of inquiry in the field of cosmopolitan ethics

    How Should We Foster the Professional Integrity of Engineers in Japan? A Pride-Based Approach

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    I discuss the predicament that engineering-ethics education in Japan now faces and propose a solution to this. The predicament is professional motivation, i.e., the problem of how to motivate engineering students to maintain their professional integrity. The special professional responsibilities of engineers are often explained either as an implicit social contract between the profession and society (the “social-contract” view), or as requirements for membership in the profession (the “membership-requirement” view). However, there are empirical data that suggest that such views will not do in Japan, and this is the predicament that confronts us. In this country, the profession of engineering did not exist 10 years ago and is still quite underdeveloped. Engineers in this country do not have privileges, high income, or high social status. Under such conditions, neither the social-contract view nor the membership-requirement view is convincing. As an alternative approach that might work in Japan, I propose a pride-based view. The notion of pride has been analyzed in the virtue-ethics literature, but the full potential of this notion has not been explored. Unlike other kinds of pride, professional pride can directly benefit the general public by motivating engineers to do excellent work even without social rewards, since being proud of themselves is already a reward. My proposal is to foster a particular kind of professional pride associated with the importance of professional services in society, as the motivational basis for professional integrity. There is evidence to suggest that this model works

    Strategies used as spectroscopy of financial markets reveal new stylized facts

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    We propose a new set of stylized facts quantifying the structure of financial markets. The key idea is to study the combined structure of both investment strategies and prices in order to open a qualitatively new level of understanding of financial and economic markets. We study the detailed order flow on the Shenzhen Stock Exchange of China for the whole year of 2003. This enormous dataset allows us to compare (i) a closed national market (A-shares) with an international market (B-shares), (ii) individuals and institutions and (iii) real investors to random strategies with respect to timing that share otherwise all other characteristics. We find that more trading results in smaller net return due to trading frictions. We unveiled quantitative power laws with non-trivial exponents, that quantify the deterioration of performance with frequency and with holding period of the strategies used by investors. Random strategies are found to perform much better than real ones, both for winners and losers. Surprising large arbitrage opportunities exist, especially when using zero-intelligence strategies. This is a diagnostic of possible inefficiencies of these financial markets.Comment: 13 pages including 5 figures and 1 tabl
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