190 research outputs found

    Thermal model at RHIC, part II: elliptic flow and HBT radii

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    We continue the analysis of the preceding talk with a discussion of the elliptic flow and the HBT pion correlation radii. It is shown that the thermal model can be extended to describe these phenomena. The description of the elliptic flow involves an appropriate deformation of the freeze-out hypersurface and flow velocity. The obtained results agree reasonably with the data for soft (< 2 GeV) transverse momenta. For the pionic HBT correlation radii the experimental feature that R_out/R_side ~ 1 is naturally obtained. The reproduction of individual R_side and R_out can be achieved with the inclusion of the excluded volume corrections, which effectively increase the radii by \~30%.Comment: Talk presented at II International Workshop on Hadron Physics, 25-29 September 2002, Coimbra, Portugal (10 pages

    pion-rho-omega vertex in nuclear matter

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    Medium modifications of the pion-omega-rho vertex are analyzed in context of the omega -> pi gamma* and rho -> pi gamma* decays in nuclear matter. A relativistic hadronic model with mesons, nucleons, and Delta(1232)isobars is applied. A substantial increase of the widths for the decays omega -> pi gamma* and rho -> pi gamma* is found for photon virtualities in the range 0.3-0.6 GeV. This enhancement has a direct importance for the description of dilepton yields obtained in relativistic heavy-ion collisions.Comment: 6 pages, to appear in Proc. 2nd International Symposium on Quantum Theory and Symmetries, Cracow, 18-21 July 200

    Dowling-Degos Disease: Case Report and Review of the Literature

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    Dowling-Degos disease (DDD) is an unusual pigmentary disorder usually caused by mutations in keratin 5. A 44-year-old woman in good general health presented due to the recent appearance of numerous pigmented macules on her axillary and anogenital skin. A biopsy showed lacy, finger-like epidermal extensions into the dermis which were heavily pigmented and associated with tiny cysts or dilated follicles. We view DDD as part of a spectrum of disorders which are morphologically related but vary in location and time of expression. In addition, both the clinical and histological differential diagnostic considerations are extensive. Copyright (C) 2010 S. Karger AG, Base

    Self-diffusion and shear viscosity for the TIP4P/Ice water model

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    With an ever-increasing interest in water properties, many intermolecular force fields have been proposed to describe the behavior of water. Unfortunately, good models for liquid water usually cannot provide simultaneously an accurate melting point for ice. For this reason, the TIP4P/Ice model was developed at targeting the melting point, and has become the preferred choice for simulating ice at coexistence. Unfortunately, available data for its dynamic properties in the liquid state are scarce. Therefore, we demonstrate a series of simulations aimed at the calculation of transport coefficients for the TIP4P/Ice model over a large range of thermodynamic conditions, ranging from T=245T=245 K to T=350T=350 K for the temperature and from p=0p=0 to p=500p=500 MPa for the pressure. We have found that the self-diffusion (shear viscosity) exhibits smaller (increased) values than TIP4P/2005 and experiments. However, rescaling the temperature with respect to the triple point temperature as in a corresponding states plot we find TIP4P/Ice compares very well with TIP4P/2005 and to experiment. Such observations allow us to infer that despite the different original purposes of these two models examined here, one can benefit from a vast number of reports regarding the behavior of transport coefficients for the TIP4P/2005 model and utilize them following the routine described in this paper

    Computing and fabricating multilayer models

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    We present a method for automatically converting a digital 3D model into a multilayer model: a parallel stack of high-resolution 2D images embedded within a semi-transparent medium. Multilayer models can be produced quickly and cheaply and provide a strong sense of an object's 3D shape and texture over a wide range of viewing directions. Our method is designed to minimize visible cracks and other artifacts that can arise when projecting an input model onto a small number of parallel planes, and avoid layer transitions that cut the model along important surface features. We demonstrate multilayer models fabricated with glass and acrylic tiles using commercially available printers

    Real-Time Volumetric Shadows using 1D Min-Max Mipmaps

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    Light scattering in a participating medium is responsible for several important effects we see in the natural world. In the presence of occluders, computing single scattering requires integrating the illumination scattered towards the eye along the camera ray, modulated by the visibility towards the light at each point. Unfortunately, incorporating volumetric shadows into this integral, while maintaining real-time performance, remains challenging. In this paper we present a new real-time algorithm for computing volumetric shadows in single-scattering media on the GPU. This computation requires evaluating the scattering integral over the intersections of camera rays with the shadow map, expressed as a 2D height field. We observe that by applying epipolar rectification to the shadow map, each camera ray only travels through a single row of the shadow map (an epipolar slice), which allows us to find the visible segments by considering only 1D height fields. At the core of our algorithm is the use of an acceleration structure (a 1D minmax mipmap) which allows us to quickly find the lit segments for all pixels in an epipolar slice in parallel. The simplicity of this data structure and its traversal allows for efficient implementation using only pixel shaders on the GPU
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