4,850 research outputs found

    [Book review] "The Economics of Involuntary Resettlement: Questions and Challenges edited by Michael M. Cernea"

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    Developing countries, Latin America, India, Community development, Settlements, Economic policy

    [Book review] "Catching Up and Falling Behind: Post-Communist Transformation in Historical Perspective by David A. Dyker"

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    Soviet, Russia, East Europe, Socialist economy, Economic development

    [Book review] "David S. Landes, The Wealth and Poverty of Nations: Why Some Are So Rich and Some So Poor"

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    Europe, Japan, China, Asia, South America, Economic history, Poverty

    Determining Minimal Polynomial of Proper Element by Using Higher Degree Traces

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    Modern communication engineerings, such as elliptic curve cryptographies, often requires algebra on finite extension field defined by modulus arithmetic with an irreducible polynomial. This paper provides a new method to detemine the minimal (irreducible) polynomial of a given proper element in finite extension field. In the conventional determination method, as we have to solve the simultaneous equations, the computation is very involved. In this paper, the well known "trace" is extended to higher degree traces. Using the new traces, we yield the coefficient formula of the desired minimal polynomial. The new method becomes very simple without solving the simultaneous equations, and about twice faster than the conventional method in computation speed

    The 1996-1997 Fading of V651 Mon, the Binary Central Star of the Planetary Nebula NGC 2346

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    V651 Mon is the binary central star of the bipolar planetary nebula NGC 2346. The star showed the second-ever deep fading in 1996-1997, which was presumably caused by obscuration by a dust cloud in the planetary nebula, as was proposed to explain the 1981-1985 event. The entire duration of the 1996-1997 event was \~400 d, remarkably shorter than the 1981-1985 event, suggesting that the obscuring body was smaller or had a larger tangential velocity. The most remarkable feature in this event was the presence of a sharply defined transient clearing (brightening). From the time-scale of the variation, we propose an upper limit of the projected scale of several times ~10^11 cm of the structure responsible for the brightening. This observation provides the first evidence for a sharply defined, small lucent structure within the obscuring body around the central star of NGC 2346Comment: 4 pages, 3 figures (using a non-standard style file

    Dirac's hole theory versus quantum field theory

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    Dirac's hole theory and quantum field theory are usually considered equivalent to each other. For models of a certain type, however, the equivalence may not hold as we discuss in this Letter. This problem is closely related to the validity of the Pauli principle in intermediate states of perturbation theory.Comment: No figure
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