18,078 research outputs found

    Studies of Stellar Collapse and Black Hole Formation with the Open-Source Code GR1D

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    We discuss results from simulations of black hole formation in failing core-collapse supernovae performed with the code GR1D, a new open-source Eulerian spherically-symmetric general-relativistic hydrodynamics code. GR1D includes rotation in an approximate way (1.5D) comes with multiple finite-temperature nuclear equations of state (EOS), and treats neutrinos in the post-core-bounce phase via a 3-flavor leakage scheme and a heating prescription. We chose the favored K_0 = 220 MeV-variant of the Lattimer & Swesty (1990) EOS and present collapse calculations using the progenitor models of Limongi & Chieffi (2006). We show that there is no direct (or “prompt”) black hole formation in the collapse of ordinary massive stars (8M_☉ â‰Č M_(ZAMS) â‰Č 100 M_☉) present first results from black hole formation simulations that include rotation

    OGY Control of Haken Like Systems on Different Poincare Sections

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    The Chua system, the Lorenz system, the Chen system and The L\"u system are chaotic systems that their state space equations is very similar to Haken system which is a nonlinear model of a optical slow-fast system. These Haken-Like Sys-tems have very similar properties. All have two slow but unstable eigenvalues and one fastest but stable eigenvalue. This lets that an approximation of slow manifold be equivalent with unstable manifold of the system. In other hand, control of discreet model of the system on a defined manifold (Poincare map) is main essence of some important control methods of chaotic systems for example OGY method. Here, by using different methods of defining slow manifold of the H-L systems the efficiency of the OGY control for stabilizing problem investigated.Comment: 4 page

    Seasonal adjustment of the money supply

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    Seasonal variations (Economics) ; Business cycles

    Statistically Locked-in Transport Through Periodic Potential Landscapes

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    Classical particles driven through periodically modulated potential energy landscapes are predicted to follow a Devil's staircase hierarchy of commensurate trajectories depending on the orientation of the driving force. Recent experiments on colloidal spheres flowing through arrays of optical traps do indeed reveal such a hierarchy,but not with the predicted structure. The microscopic trajectories, moreover,appear to be random, with commensurability emerging only in a statistical sense. We introduce an idealized model for periodically modulated transport in the presence of randomness that captures both the structure and statistics of such statistically locked-in states.Comment: REVTeX with EPS figures, 4 pages, 4 figure

    Taking the lead: post-2012 climate targets for the North: towards adequate and equitable future climate commitments for industrialised countries

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    Any definition of adequacy consistent with the objective of the Climate Convention will require increased mitigation efforts in industrialized countries far beyond those levels agreed in Kyoto. This paper, therefore, focuses on future reduction targets for industrialised (Annex I) countries. It starts with an assessment of mid- and long-term targets already adopted in industrialised countries against the backdrop of required emission cuts to keep climate change within tolerable limits. Taking into account their heterogeneous national circumstances, the main part of the paper presents a method for differentiating Annex I countries with a view to assigning future mitigation and financial transfer commitments. This differentiation exercise is based on an analytical approach that was developed in the project “South-North Dialogue – Equity in the Greenhouse". Slightly modifying the original approach the level of reduction targets is determined by the two criteria of “responsibility" and “potential" to mitigate. Obligations to provide financial and technological resources to developing countries, on the other hand, are to be assigned according to the “capability" criteria. --

    Spectrum of the Andreev Billiard and Giant Fluctuations of the Ehrenfest Time

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    The density of states in the semiclassical Andreev billiard is theoretically studied and shown to be determined by the fluctuations of the classical Lyapunov exponent λ\lambda. The rare trajectories with a small value of λ\lambda give rise to an anomalous increase of the Ehrenfest time τE≈∣ln⁡ℏ∣/λ\tau_E\approx |\ln\hbar|/\lambda and, consequently, to the appearance of Andreev levels with small excitation energy. The gap in spectrum is obtained and fluctuations of the value of the gap due to different positions of superconducting lead are considered.Comment: 4 pages, 3 figure
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