17,168 research outputs found

    Steady-states and kinetics of ordering in bus-route models: connection with the Nagel-Schreckenberg model

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    A Bus Route Model (BRM) can be defined on a one-dimensional lattice, where buses are represented by "particles" that are driven forward from one site to the next with each site representing a bus stop. We replace the random sequential updating rules in an earlier BRM by parallel updating rules. In order to elucidate the connection between the BRM with parallel updating (BRMPU) and the Nagel-Schreckenberg (NaSch) model, we propose two alternative extensions of the NaSch model with space-/time-dependent hopping rates. Approximating the BRMPU as a generalization of the NaSch model, we calculate analytically the steady-state distribution of the {\it time headways} (TH) which are defined as the time intervals between the departures (or arrivals) of two successive particles (i.e., buses) recorded by a detector placed at a fixed site (i.e., bus stop) on the model route. We compare these TH distributions with the corresponding results of our computer simulations of the BRMPU, as well as with the data from the simulation of the two extended NaSch models. We also investigate interesting kinetic properties exhibited by the BRMPU during its time evolution from random initial states towards its steady-states.Comment: Accepted for publication in EPJ

    A payload to evaluate photodiodes for the detection of soft and hard x rays in a space environment using a Get Away Special

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    We propose to use the Get Away Special (GAS) facility to evaluate P-intrinsic-N (PIN) detectors and avalanche photodiodes (APD's) for the detection of both solar and nonsolar soft and hard x rays. We would like to fly both types of silicon detectors for the direct detection of the x ray photons in the energy range from 1 to 30 keV with an energy resolution of about 1 keV. We would also like to use both types of photodiodes viewing CsI(Tl) scintillators to extend the energy range up to 1 MeV with -6 percent resolution at 660 keV. Solar flares would be detected with this instrumentation during periods of solar pointing providing high energy resolution spectra with high time resolution. Similar data would be obtained in the scanning mode on nonsolar transient and steady x ray sources with the same instrumentation. A commandable door over the detectors would be required to allow measurements to be made as low as 1 keV

    The Comovement of Returns and Investment Within the Multinational Firm

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    Can financial integration, particularly the cross-border investments of multinational firms, help explain the synchronization of business cycles? This paper presents evidence on the comovement of returns and investment within U.S. multinational firms to address this question. These firms constitute significant fractions of economic output and investment in most large economies, suggesting that they could create significant economic linkages. Aggregate measures of rates of return and investment rates of U.S. multinational firms located in different countries are highly correlated across countries. Firm-level regressions demonstrate that rates of return and investment rates of affiliates are highly correlated with the rates of return and investment of the affiliate's parent and other affiliates within the same parent system, controlling for country and industry factors. The evidence on these interrelationships and the importance of multinationals to local economies suggests that global firms may be an important channel for transmitting economic shocks. This evidence also sheds light on asset pricing puzzles related to the diversification benefits provided by multinational firms.

    Research and development of open-cycle fuel cells Fourth quarterly progress report, period ending Aug. 15, 1965

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    Digital computer program for minimizing weight of fuel cell power systems - prelaunch startup and instrumentation - mathematical model of static moisture removal process - fuel cell mode

    A MEMS electrostatic particle transportation system

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    We demonstrate here an electrostatic MEMS system capable of transporting particles 5-10ÎĽm in diameter in air. This system consists of 3-phase electrode arrays covered by insulators (Figs. 1, 2). Extensive testing of this system has been done using a variety of insulation materials (silicon nitride, photoresist, and Teflon), thickness (0- 12ÎĽm), particle sizes (1-10ÎĽm), particle materials (metal, glass, polystyrene, spores, etc), waveforms, frequencies, and voltages. Although previous literature [1-2] claimed it impractical to electrostatically transport particles with sizes 5-10ÎĽm due to complex surface forces, this effort actually shows it feasible (as high as 90% efficiency) with the optimal combination of insulation thickness, electrode geometry, and insulation material. Moreover, we suggest a qualitative theory for our particle transportation system which is consistent with our data and finite-element electrostatic simulations

    Attacking Brandenburg with History: Does the Long-Term Harm of Biased Speech Justify a Criminal Statute Suppressing It?

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    Book Review: Destructive Messages: How Hate Speech Paves the Way for Harmful Social Movements, Alexander Tsesis, New York: New York University Press, 2002, 246 pages. A review of Alexander Tsesis\u27s Destructive Messages: How Hate Speech Paves the Way for Harmful Social Movements, New York University Press, 2002. At one level, Alexander Tsesis\u27s thesis is simply one in a long line of arguments about the need to regulate racist speech. Yet on another level, it is fundamentally different from much American literature on hate speech because Tsesis draws on a broad historical swath, and because he contends that the United States should regulate hate speech due to a causal link between that speech and oppression of such magnitude as the Holocaust and slavery. Moreover, it is fundamentally different because Tsesis focuses on the ideology of racial inferiority and not where most proponents of regulating hate speech in the past have set their sights-epithets, or what one could term verbal assaults. At the end of his book, Tsesis proposes a model statute for criminalizing hate speech
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