596 research outputs found

    Applicability of a Representation for the Martin's Real-Part Formula in Model-Independent Analyses

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    Using a novel representation for the Martin's real-part formula without the full scaling property, an almost model-independent description of the proton-proton differential cross section data at high energies (19.4 GeV - 62.5 GeV) is obtained. In the impact parameter and eikonal frameworks, the extracted inelastic overlap function presents a peripheral effect (tail) above 2 fm and the extracted opacity function is characterized by a zero (change of sign) in the momentum transfer space, confirming results from previous model-independent analyses. Analytical parametrization for these empirical results are introduced and discussed. The importance of investigations on the inverse problems in high-energy elastic hadron scattering is stressed and the relevance of the proposed representation is commented. A short critical review on the use of Martin's formula is also presented.Comment: Two comments and one reference added at the end of Subsec. 3.3; 23 pages, 9 figures; to be published in Int. J. Mod. Phys.

    Intravascular myopericytoma in the heel: Case report and literature review

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    Intravascular myopericytoma (IVMP), regarded as a variant of myopericytoma, is a rare tumor. Very few cases have been described, none in the foot. The first case of IVMP located in the heel of the foot is described in this article. A literature review is reported of all cases of IVMP published in the English literature. A 48-year-old man possessed an IVMP on the heel of the right foot. The physical examination and histopathological and ultrasound studies are described. The literature review yielded 5 cases of IVMP, 2 of which were in the thigh and 1 each in the oral mucosa, the periorbital region, and the leg. The possibility that these lesions may be malignant suggests that the histopathological study of vascular tumors should include immunohistochemical tests

    A new surgical procedure for hallux limitus treatment: Double-V osteotomy on the base of the proximal phalanx of the hallux

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    The purpose of this study was to evaluate the effectiveness of the new Double-V osteotomy of the first metatarsophalangeal joint (1 st MPJ) in patients with hallux limitus (HL). A study of 66 patients was performed, 33 patients were treated Cheilectomy and 33 were treated Double-V. All patients underwent an assessment of the passive mobility of the 1 st MPJ before the procedure, reevaluated 12 months later evaluating dorsiflexion, plantarflexion, and patients status using both the American Orthopaedic Foot and Ankle Society (AOFAS) for Hallux Metatarsophalangeal-Interphalangeal Scale. In comparing the improvement achieved regarding the increase of mobility obtained with surgical treatment, the feet operated with procedure Double-V gained significant degrees of movement increased in all analyzed parameters (P<.05). We achieved 13.33° more than average in dorsiflexion motion and 2.12° more than average in plantarflexion with regard to the feet that were operated with Cheilectomy procedure. Double-V scores on the AOFAS scale improved significantly (P=.000) 91.48 points postoperative, while with the following Cheilectomy only 79.30 points. This new surgical technique, easy to perform and with low complexity in surgical execution and a minimum of complications, produces better clinical and functional results that Cheilectomy alone

    A model for net-baryon rapidity distribution

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    In nuclear collisions, a sizable fraction of the available energy is carried away by baryons. As the baryon number is conserved, the net-baryon B−BˉB-\bar{B} retains information on the energy-momentum carried by the incoming nuclei. A simple and consistent model for net-baryon production in high energy proton-proton and nucleus-nucleus collisions is presented. The basic ingredients of the model are valence string formation based on standard PDFs with QCD evolution and string fragmentation via the Schwinger mechanism. The results of the model are presented and compared with data at different centre-of-mass energies and centralities, as well as with existing models. These results show that a good description of the main features of net-baryon data is possible in the framework of a simplistic model, with the advantage of making the fundamental production mechanisms manifest.Comment: 9 pages, 12 figures; in fig. 11 a) the vertical scale was correcte

    Factorial Moments in a Generalized Lattice Gas Model

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    We construct a simple multicomponent lattice gas model in one dimension in which each site can either be empty or occupied by at most one particle of any one of DD species. Particles interact with a nearest neighbor interaction which depends on the species involved. This model is capable of reproducing the relations between factorial moments observed in high--energy scattering experiments for moderate values of DD. The factorial moments of the negative binomial distribution can be obtained exactly in the limit as DD becomes large, and two suitable prescriptions involving randomly drawn nearest neighbor interactions are given. These results indicate the need for considerable care in any attempt to extract information regarding possible critical phenomena from empirical factorial moments.Comment: 15 pages + 1 figure (appended as postscript file), REVTEX 3.0, NORDITA preprint 93/4

    Production of Secondaries in High Energy d+Au Collisions

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    In the framework of Quark-Gluon String Model we calculate the inclusive spectra of secondaries produced in d+Au collisions at intermediate (CERN SPS) and at much higher (RHIC) energies. The results of numerical calculations at intermediate energies are in reasonable agreement with the data. At RHIC energies numerically large inelastic screening corrections (percolation effects) should be accounted for in calculations. We extract these effects from the existing RHIC experimental data on minimum bias and central d+Au collisions. The predictions for p+Au interactions at LHC energy are also given.Comment: 18 pages and 10 figure

    Percolation of Color Sources and the determination of the Equation of State of the Quark-Gluon Plasma (QGP) produced in central Au-Au collisions at \sqrt S_{NN}= 200 GeV

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    The Color String Percolation Model (CSPM) is used to determine the equation of state (EOS) of the QGP produced in central Au-Au collisions at sNN\sqrt{s_{NN}} = 200 A GeV using STAR data at RHIC. When the initial density of interacting colored strings exceeds the 2D percolation threshold a cluster is formed, which defines the onset of color deconfinement. These interactions also produce fluctuations in the string tension which transforms the Schwinger particle (gluon) production mechanism into a maximum entropy thermal distribution. The single string tension is determined by identifying the known value of the universal hadron limiting temperature TcT_{c} = 167.7 ±\pm 2.6 MeV with the CSPM percolation temperature at the critical threshold ξc\xi_{c} =1.2. At mid-rapidity the initial Bjorken energy density and the initial temperature determine the number of degrees of freedom consistent with the formation of a ∼\sim 2+1 flavor QGP. An analytic expression for the equation of state, the sound velocity Cs2(ξ)C_{s}^{2}(\xi) is obtained in CSPM. The CSPM Cs2(ξ)C_{s}^{2}(\xi) and the bulk thermodynamic values ε/T4\varepsilon /T^{4} and s/T3s /T^{3} are in excellent agreement in the phase transition region with recent lattice QCD simulations (LQCD) by the HotQCD Collaboration.Comment: 4 pages, 3 figure
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