23,581 research outputs found

    Another construction of edge-regular graphs with regular cliques

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    We exhibit a new construction of edge-regular graphs with regular cliques that are not strongly regular. The infinite family of graphs resulting from this construction includes an edge-regular graph with parameters (24,8,2)(24,8,2). We also show that edge-regular graphs with 11-regular cliques that are not strongly regular must have at least 2424 vertices.Comment: 7 page

    A Cross-National Comparison of Consumers\u27 Attitudes Toward Direct Marketing and Purchase Intention

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    Existing research indicates that attitudes toward the three elements of direct marketing (the source, mode, and response channel) influence consumers\u27 intentions to purchase directly marketed products. While research investigating attitudes and consumers\u27 response has been conducted in the U.S., there has been no research to date which examines attitude structures and purchase intentions towards direct marketing in a multi-country setting, in spite of the standardized global efforts of direct marketeers. This study presents findings on attitude structures regarding direct marketing for three affluent open markets, the U.S., Singapore, and the Netherlands and empirically investigates the relationships between these consumers\u27 attitudes toward the three elements of direct marketing and purchase intentions

    Bayesian analysis of endogenous delay threshold models

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    We develop Bayesian methods of analysis for a new class of threshold autoregressive models: endogenous delay threshold. We apply our methods to the commonly used sunspot data set and find strong evidence in favor of the Endogenous Delay Threshold Autoregressive (EDTAR) model over linear and traditional threshold autoregressions

    Does Size Matter? School Consolidation Policy Issues in Arkansas

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    Providing a reasonable education for all students in Arkansas is a legal responsibility explicitly mandated by the state’s constitution. Consistent with the long-standing American tradition of “grassroots” control of education, public schools in all states are funded and managed first and foremost at the local level. The federal government can and does enact legislation with which schools must conform. Directly or indirectly, federal mandates provide significant amounts of monies to support particular types of school services and programming. But ultimate responsibility for financing and operating schools devolves on state government. In Arkansas, it has been held, the state must provide “a general, suitable, and efficient system of free public schools” (Lakeview v. Huckabee, 2001)

    Herschel dust emission as a probe of starless cores mass: MCLD 123.5+24.9 of the Polaris Flare

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    We present newly processed archival Herschel images of molecular cloud MCLD 123.5+24.9 in the Polaris Flare. This cloud contains five starless cores. Using the spectral synthesis code Cloudy, we explore uncertainties in the derivation of column densities, hence, masses of molecular cores from Herschel data. We first consider several detailed grain models that predict far-IR grain opacities. Opacities predicted by the models differ by more than a factor of two, leading to uncertainties in derived column densities by the same factor. Then we consider uncertainties associated with the modified blackbody fitting process used by observers to estimate column densities. For high column density clouds (N(H) \gg 1022^{22} cm2^{-2}), this fitting technique can underestimate column densities by about a factor of three. Finally, we consider the virial stability of the five starless cores in MCLD 123.5+24.9. All of these cores appear to have strongly sub-virial masses, assuming, as we argue, that 13^{13}CO line data provide reliable estimates of velocity dispersions. Evidently, they are not self-gravitating, so it is no surprise that they are starless.Comment: ApJ, Accepted. Minor typographical errors corrected and figures 6 & 7 updated in v

    Coronal heating by magnetohydrodynamic turbulence driven by reflected low-frequency waves

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    A candidate mechanism for the heating of the solar corona in open field line regions is described. The interaction of Alfvén waves, generated in the photosphere or chromosphere, with their reflections and the subsequent driving of quasi-two-dimensional MHD turbulence is considered. A nonlinear cascade drives fluctuations toward short wavelengths which are transverse to the mean field, thereby heating at rates insensitive to restrictive Alfvén timescales. A phenomenology is presented, providing estimates of achievable heating efficiency that are most favorable

    A reduced magnetohydrodynamic model of coronal heating in open magnetic regions driven by reflected low-frequency waves

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    A reduced magnetohydrodynamic (RMHD) description is employed to examine a suggestion made by W. H. Matthaeus and colleagues in 1999 that coronal heating might be sustained by a cascade of low-frequency MHD turbulence. Here RMHD simulations show that the low-frequency cascade to high transverse wavenumbers can be driven by an externally maintained flux of low-frequency propagating Alfvén waves, in combination with reflection caused by an inhomogeneous background medium. The simulations show that the suggestions made previously on the basis of a phenomenology are indeed realizable. In addition, the effect is seen to sensitively depend on the presence of reflection, as the background turbulence level needed to maintain the cascade can be sustained only when reflection is imposed. The steady level of turbulence is insensitive to the initial seed turbulence level (provided it is nonzero). Consequences of this model for realistic models of coronal heating in open field-line regions are discussed

    Microscopy of glazed layers formed during high temperature sliding wear at 750C

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    The evolution of microstructures in the glazed layer formed during high temperature sliding wear of Nimonic 80A against Stellite 6 at 750 ◦C using a speed of 0.314ms−1 under a load of 7N has been investigated using scanning electron microscopy (SEM), energy dispersive analysis by X-ray (EDX), X-ray diffraction (XRD) analysis, scanning tunnelling microscopy (STM) and transmission electron microscopy (TEM). The results indicate the formation of a wear resistant nano-structured glazed layer. The mechanisms responsible for the formation of the nano-polycrystalline glazed layer are discussed
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