3,061 research outputs found

    An Overview on Institutionalism and Decentralized Decision-Making

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    Human actions, interactions and decisions should have a certain degree of predictability that can be obtained by establishing rules. Institutions, in general, are defined by sets of rules known by the public and applicable for the community. Their existence is essential for the economic activity, as it cannot develop in a vacuum. At the same time, the type and the quality of institutions make the difference in implementing economic aspirations of individuals and in supporting economic overall growth. Institutions provide a minimum of regulations that in conjunction with the particularities and the interests of individuals and communities become the foundation for economic, political and social decision-making processes.

    Thomas Hobbes\u27 Theory of Obligation: A Modern Interpretation

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    Harmonic generation of gravitational wave induced Alfven waves

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    Here we consider the nonlinear evolution of Alfven waves that have been excited by gravitational waves from merging binary pulsars. We derive a wave equation for strongly nonlinear and dispersive Alfven waves. Due to the weak dispersion of the Alfven waves, significant wave steepening can occur, which in turn implies strong harmonic generation. We find that the harmonic generation is saturated due to dispersive effects, and use this to estimate the resulting spectrum. Finally we discuss the possibility of observing the above process.Comment: 7 page

    Diffusion of particles in an expanding sphere with an absorbing boundary

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    We study the problem of particles undergoing Brownian motion in an expanding sphere whose surface is an absorbing boundary for the particles. The problem is akin to that of the diffusion of impurities in a grain of polycrystalline material undergoing grain growth. We solve the time dependent diffusion equation for particles in a d-dimensional expanding sphere to obtain the particle density function (function of space and time). The survival rate or the total number of particles per unit volume as a function of time is evaluated. We have obtained particular solutions exactly for the case where d=3 and a parabolic growth of the sphere. Asymptotic solutions for the particle density when the sphere growth rate is small relative to particle diffusivity and vice versa are derived.Comment: 12 pages. To appear in J. Phys. A: Math. Theor. 41 (2008

    Nonlinear Interactions Between Gravitational Radiation and Modified Alfven Modes in Astrophysical Dusty Plasmas

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    We present an investigation of nonlinear interactions between Gravitational Radiation and modified Alfv\'{e}n modes in astrophysical dusty plasmas. Assuming that stationary charged dust grains form neutralizing background in an electron-ion-dust plasma, we obtain the three wave coupling coefficients, and calculate the growth rates for parametrically coupled gravitational radiation and modified Alfv\'{e}n-Rao modes. The threshold value of the gravitational wave amplitude associated with convective stabilization is particularly small if the gravitational frequency is close to twice the modified Alfv\'en wave-frequency. The implication of our results to astrophysical dusty plasmas is discussed.Comment: A few typos corrected. Published in Phys. Rev.

    Percutaneous Management of Pyogenic Hepatic Abscesses

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    Twelve patients (9 men, 3 women) with a mean age of 65 (54-78) years, with pyogenic hepatic abscesses were managed by percutaneous drainage between 1979 and 1987. Biliary origin was most common (4 patients), followed by hepatic abscesses as a late postoperative complication (seen in 3 patients) and hepatic abscesses occurring in association with acute appendicitis (2 patients). The origin was unknown in 3 patients. Diagnosis was reached by computed tomography or ultrasonography with a diagnostic delay of in mean 11 days. Seventeen abscesses were found among the 12 patients. The median abscess size (maximal diameter) was 7 (1-12) cm. Nine patients were treated with percutaneous drainage with an indwelling catheter within the abscess cavity for up to 3 weeks, while 3 patients were managed with percutaneous puncture and aspiration alone. The most commonly isolated organism from the drained hepatic abscess was E. coli. The course following percutaneous treatment was uneventful, without mortality and recurrence of the hepatic abscess during follow-up. One patient required surgical drainage of an additional hepatic abscess. Percutaneous drainage of hepatic abscesses, independent of origin, thus seems as a safe and reliable method, which should be considered as the treatment of choice if facilities and knowledge of percutaneous management are provided

    Electromechanical Piezoresistive Sensing in Suspended Graphene Membranes

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    Monolayer graphene exhibits exceptional electronic and mechanical properties, making it a very promising material for nanoelectromechanical (NEMS) devices. Here, we conclusively demonstrate the piezoresistive effect in graphene in a nano-electromechanical membrane configuration that provides direct electrical readout of pressure to strain transduction. This makes it highly relevant for an important class of nano-electromechanical system (NEMS) transducers. This demonstration is consistent with our simulations and previously reported gauge factors and simulation values. The membrane in our experiment acts as a strain gauge independent of crystallographic orientation and allows for aggressive size scalability. When compared with conventional pressure sensors, the sensors have orders of magnitude higher sensitivity per unit area.Comment: 20 pages, 3 figure
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