2,084 research outputs found

    The blob and the block. When the rhetoric of the smooth and the striated went all wrong

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    This paper conforms to a view of architecture and the distribution of urban space as bio-political parameters of dominance and resistance. Using G. Deleuze & F. Guattari’s seminal essay on 1444. The Smooth and the Striated, I intend to show how Global Capitalism, by replicating the discourse of the smooth and the ungraspable, has voided Dialectics of its subversive potential.El presente artículo contempla la arquitectura y la distribución del espacio urbano como parámetros biopolíticos de dominación y resistencia. Valiéndose del ensayo 1444. Lo liso y lo estriado, de Gilles Deleuze & Felix Guattari, se pretende demostrar cómo el capitalismo global, gracias a su capacidad para emular el discurso de lo fluido y lo intangible, habrá conseguido despojar a lo dialéctico de su potencial subversivo

    Ab initio simulations of accretion disks instability

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    We show that accretion disks, both in the subcritical and supercritical accretion rate regime, may exhibit significant amplitude luminosity oscillations. The luminosity time behavior has been obtained by performing a set of time-dependent 2D SPH simulations of accretion disks with different values of alpha and accretion rate. In this study, to avoid any influence of the initial disk configuration, we produced the disks injecting matter from an outer edge far from the central object. The period of oscillations is 2 - 50 s respectively for the two cases, and the variation amplitude of the disc luminosity is 10^38 - 10^39 erg/s. An explanation of this luminosity behavior is proposed in terms of limit cycle instability: the disk oscillates between a radiation pressure dominated configuration (with a high luminosity value) and a gas pressure dominated one (with a low luminosity value). The origin of this instability is the difference between the heat produced by viscosity and the energy emitted as radiation from the disk surface (the well-known thermal instability mechanism). We support this hypothesis showing that the limit cycle behavior produces a sequence of collapsing and refilling states of the innermost disk region.Comment: 11 pages, 15 Postscript figures, uses natbib.sty, accepted for publication in MNRA

    Decays Z' -> \gamma\gamma\gamma{} and Z -> \gamma\gamma\gamma{} in the minimal 331 model

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    The possibility of a significant effect of exotic particles on the Z'->\gamma\gamma\gamma{} and Z->\gamma\gamma\gamma{} decays is investigated in the context of the minimal 331 model. This model, which is based in the SU_C(3)xSU_L(3)xU_X(1) gauge group, predicts the existence of many exotic charged particles that can significantly enhance the decay widths. It is found that the standard model prediction for the Z->\gamma\gamma\gamma{} decay remains essentially unchanged, as the new physics effects quickly decouples. On the other hand, it is found that the contributions of the new exotic quarks and gauge bosons predicted by this model lead to a branching fraction for the Z'->\gamma\gamma\gamma{} decay of about 10^(-6), which is about three orders of magnitude larger than that of the Z->\gamma\gamma\gamma{} decay.Comment: 20 pages and 20 figure

    Sub-Planck phase-space structures and Heisenberg-limited measurements

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    We show how sub-Planck phase-space structures in the Wigner function can be used to achieve Heisenberg-limited sensitivity in weak force measurements. Nonclassical states of harmonic oscillators, consisting of superpositions of coherent states, are shown to be useful for the measurement of weak forces that cause translations or rotations in phase space, which is done by entangling the quantum oscillator with a two-level system. Implementations of this strategy in cavity QED and ion traps are described.Comment: 7 pages, 2 figure

    Promoting post-stroke recovery through focal or whole body vibration: criticisms and prospects from a narrative review

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    Objective: Several focal muscle vibration (fMV) and whole body vibration (WBV) protocols have been designed to promote brain reorganization processes in patients with stroke. However, whether fMV and WBV should be considered helpful tools to promote post-stroke recovery remains still largely unclear. Methods: We here achieve a comprehensive review of the application of fMV and WBV to promote brain reorganization processes in patients with stroke. By first discussing the putative physiological basis of fMV and WBV and then examining previous observations achieved in recent randomized controlled trials (RCT) in patients with stroke, we critically discuss possible strength and limitations of the currently available data. Results: We provide the first systematic assessment of fMV studies demonstrating some improvement in upper and lower limb functions, in patients with chronic stroke. We also confirm and expand previous considerations about the rather limited rationale for the application of current WBV protocols in patients with chronic stroke. Conclusion: Based on available information, we propose new recommendations for optimal stimulation parameters and strategies for recruitment of specific stroke populations that would more likely benefit from future fMV or WBV application, in terms of speed and amount of post-stroke functional recovery

    Radiative Shocks in Rotating Accretion Flows around Black Holes

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    It is well known that the rotating inviscid accretion flows with adequate injection parameters around black holes could form shock waves close to the black holes, after the flow passes through the outer sonic point and can be virtually stopped by the centrifugal force. We examine numerically such shock waves in 1D and 2D accretion flows, taking account of cooling and heating of the gas and radiation transport. The numerical results show that the shock location shifts outward compared with that in the adiabatic solutions and that the more rarefied ambient density leads to the more outward shock location. In the 2D-flow, we find an intermediate frequency QPO behavior of the shock location as is observed in the black hole candidate GRS 1915+105.Comment: 11pages, 5 Postscript figures, to appear in PASJ, Vol.56, No.3, 200
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