70,582 research outputs found

    Multi-Frequency Magnonic Logic Circuits for Parallel Data Processing

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    We describe and analyze magnonic logic circuits enabling parallel data processing on multiple frequencies. The circuits combine bi-stable (digital) input/output elements and an analog core. The data transmission and processing within the analog part is accomplished by the spin waves, where logic 0 and 1 are encoded into the phase of the propagating wave. The latter makes it possible to utilize a number of bit carrying frequencies as independent information channels. The operation of the magnonic logic circuits is illustrated by numerical modeling. We also present the estimates on the potential functional throughput enhancement and compare it with scaled CMOS. The described multi-frequency approach offers a fundamental advantage over the transistor-based circuitry and may provide an extra dimension for the Moor's law continuation. The shortcoming and potentials issues are also discussed

    Sphaleron Transition Rate in Presence of Dynamical Fermions

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    We investigate the effect of dynamical fermions on the sphaleron transition rate at finite temperature for the Abelian Higgs model in one spatial dimension. The fermion degrees of freedom are included through bosonization. Using a numerical simulation, we find that massless fermions do not change the rate within the measurement accuracy. Surprisingly, the exponential dependence of the sphaleron energy on the Yukawa coupling is not borne out by the transition rate, which shows a very weak dependence on the fermion mass.Comment: 20 pages, 7 figures, LaTeX, psfi

    Limits on Lorentz Violation from the Highest Energy Cosmic Rays

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    We place several new limits on Lorentz violating effects, which can modify particles' dispersion relations, by considering the highest energy cosmic rays observed. Since these are hadrons, this involves considering the partonic content of such cosmic rays. We get a number of bounds on differences in maximum propagation speeds, which are typically bounded at the 10^{-21} level, and on momentum dependent dispersion corrections of the form v = 1 +- p^2/Lambda^2, which typically bound Lambda > 10^{21} GeV, well above the Planck scale. For (CPT violating) dispersion correction of the form v = 1 + p/Lambda, the bounds are up to 15 orders of magnitude beyond the Planck scale.Comment: 24 pages, no figures. Added references, very slight changes. Version published in Physical Review

    Effects of wind on turbofan engines in outdoor static test stands

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    Wind can affect measured thrust and can cause turbofan engine speed to fluctuate during outdoor testing. Techniques used at an outdoor test stand at NASA Lewis Research Center to make testing easier and faster and to improve data repeatability include using an inflow control device (ICD) to make fan speed steadier, taking many raw data samples for better averaging, and correcting thrust for wind direction and speed. Data from engine tests are presented to show that the techniques improve repeatability of thrust and airflow measurements under various wind conditions

    Changing Income Inequality and Immigration in Canada 1980-1995

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    While there is a general consensus that income inequality has increased in most developed countries over the last two decades, the analytical focus has been at the national scale. However, these increases in inequality have not been uniform across different segments of society, either in terms of social group or geographic region. In particular, the high levels of immigration to metropolitan Canada have contributed to growing inequality. Using micro-level data on household income from the 1981,1986,1991 and 1996 censuses, this paper identifies the role of immigration and its differential impact on metropolitan and non-metropolitan areas. The impacts accelerated during the first half of the 1990s when immigration remained high yet the economy slowed. The evidence suggests that the overall impact of immigration is a relatively short-run phenomenon as recent immigrants take time to adjust to the labour market. If recent immigrants are excluded, inequality is still increasing, but at a slower rate, especially in the largest metropolitan areas.income inequality; immigration

    Geographic Dimensions of Aging in Canada 1991-2001

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    Although population aging at the national level has received much attention, its geographical dimensions have not. Here we explore the demographic processes which underlie population aging at the provincial and metropolitan scale for the periods 1991-1996 and 1996-2001. A demographic accounting framework is proposed which differentiates between the effects of aging-in-place and net migration on population aging. We also examine the relationships between the various measures of aging and social and economic characteristics of metropolitan areas over the two periods. We demonstrate that the path of population aging is susceptible to social and economic context; in particular, the struggles of the British Columbian economy in the second half of the decade and the deteriorating economies of older resources based communities are associated with increases in population aging over and above the general aging taking place in Canadian society.population aging; geographic differences

    Fractal dimension of interfaces in Edwards-Anderson spin glasses for up to six space dimensions

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    The fractal dimension of domain walls produced by changing the boundary conditions from periodic to anti-periodic in one spatial direction is studied using both the strong-disorder renormalization group and the greedy algorithm for the Edwards-Anderson Ising spin-glass model for up to six space dimensions. We find that for five or less space dimensions, the fractal dimension is less than the space dimension. This means that interfaces are not space filling, thus implying replica symmetry breaking is absent in space dimensions fewer than six. However, the fractal dimension approaches the space dimension in six dimensions, indicating that replica symmetry breaking occurs above six dimensions. In two space dimensions, the strong-disorder renormalization group results for the fractal dimension are in good agreement with essentially exact numerical results, but the small difference is significant. We discuss the origin of this close agreement. For the greedy algorithm there is analytical expectation that the fractal dimension is equal to the space dimension in six dimensions and our numerical results are consistent with this expectation.Comment: 6 pages, 5 figures, 1 tabl
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